diff --git a/models/auth/oauth2.go b/models/auth/oauth2.go
index 9acd9a46b0..9ef89cb624 100644
--- a/models/auth/oauth2.go
+++ b/models/auth/oauth2.go
@@ -6,6 +6,7 @@ package auth
 import (
 	"context"
 	"crypto/sha256"
+	"crypto/subtle"
 	"encoding/base32"
 	"encoding/base64"
 	"errors"
@@ -151,9 +152,9 @@ func (app *OAuth2Application) ContainsRedirectURI(redirectURI string) bool {
 	// https://openid.net/specs/openid-connect-core-1_0.html#AuthRequest
 	// https://datatracker.ietf.org/doc/html/draft-ietf-oauth-security-topics-12#section-3.1
 	contains := func(s string) bool {
-		s = strings.TrimSuffix(strings.ToLower(s), "/")
+		s = strings.TrimSuffix(util.ToUpperASCII(s), "/")
 		for _, u := range app.RedirectURIs {
-			if strings.TrimSuffix(strings.ToLower(u), "/") == s {
+			if strings.TrimSuffix(util.ToUpperASCII(u), "/") == s {
 				return true
 			}
 		}
@@ -408,26 +409,41 @@ func (code *OAuth2AuthorizationCode) GenerateRedirectURI(state string) (*url.URL
 	return redirect, err
 }
 
-// Invalidate deletes the auth code from the database to invalidate this code
+// Invalidate deletes the auth code from the database to invalidate this code.
+// It returns an error if the code was already invalidated (i.e., no rows were deleted),
+// which prevents authorization code replay attacks.
 func (code *OAuth2AuthorizationCode) Invalidate(ctx context.Context) error {
-	_, err := db.GetEngine(ctx).ID(code.ID).NoAutoCondition().Delete(code)
-	return err
+	affected, err := db.GetEngine(ctx).ID(code.ID).NoAutoCondition().Delete(code)
+	if err != nil {
+		return err
+	}
+	if affected == 0 {
+		return fmt.Errorf("authorization code already used or does not exist")
+	}
+	return nil
 }
 
-// ValidateCodeChallenge validates the given verifier against the saved code challenge. This is part of the PKCE implementation.
+// ValidateCodeChallenge validates the given verifier against the saved code challenge. This is part of the PKCE
+// implementation. If a code challenge was set during authorization, a valid verifier MUST be provided.
 func (code *OAuth2AuthorizationCode) ValidateCodeChallenge(verifier string) bool {
+	// If no PKCE was used during authorization, no verifier is needed.
+	if code.CodeChallengeMethod == "" && code.CodeChallenge == "" {
+		return true
+	}
+	// A challenge was set but no verifier provided: reject outright, no comparison or hashing is required.
+	if verifier == "" {
+		return false
+	}
 	switch code.CodeChallengeMethod {
 	case "S256":
 		// base64url(SHA256(verifier)) see https://tools.ietf.org/html/rfc7636#section-4.6
 		h := sha256.Sum256([]byte(verifier))
 		hashedVerifier := base64.RawURLEncoding.EncodeToString(h[:])
-		return hashedVerifier == code.CodeChallenge
+		return subtle.ConstantTimeCompare([]byte(hashedVerifier), []byte(code.CodeChallenge)) == 1
 	case "plain":
-		return verifier == code.CodeChallenge
-	case "":
-		return true
+		return subtle.ConstantTimeCompare([]byte(verifier), []byte(code.CodeChallenge)) == 1
 	default:
-		// unsupported method -> return false
+		// unsupported or empty method with a non-empty challenge -> reject
 		return false
 	}
 }
@@ -490,16 +506,19 @@ func (grant *OAuth2Grant) GenerateNewAuthorizationCode(ctx context.Context, redi
 }
 
 // IncreaseCounter increases the counter and updates the grant
+// IncreaseCounter atomically increments the counter only if it still matches
+// the value loaded into this grant. Returns an error if the counter was already
+// changed by a concurrent request (refresh token replay).
 func (grant *OAuth2Grant) IncreaseCounter(ctx context.Context) error {
-	_, err := db.GetEngine(ctx).ID(grant.ID).Incr("counter").Update(new(OAuth2Grant))
+	affected, err := db.GetEngine(ctx).Where("id = ? AND counter = ?", grant.ID, grant.Counter).
+		Incr("counter").Update(new(OAuth2Grant))
 	if err != nil {
 		return err
 	}
-	updatedGrant, err := GetOAuth2GrantByID(ctx, grant.ID)
-	if err != nil {
-		return err
+	if affected == 0 {
+		return fmt.Errorf("grant counter changed unexpectedly (possible replay)")
 	}
-	grant.Counter = updatedGrant.Counter
+	grant.Counter++
 	return nil
 }
 
diff --git a/models/auth/oauth2_test.go b/models/auth/oauth2_test.go
index 9c6836ed0d..aa474393c1 100644
--- a/models/auth/oauth2_test.go
+++ b/models/auth/oauth2_test.go
@@ -75,6 +75,13 @@ func TestOAuth2Application_ContainsRedirect_Slash(t *testing.T) {
 	assert.False(t, app.ContainsRedirectURI("http://127.0.0.1/other"))
 }
 
+func TestOAuth2Application_ContainsRedirect_Normalization(t *testing.T) {
+	app := &auth_model.OAuth2Application{RedirectURIs: []string{"https://website.com"}}
+	assert.True(t, app.ContainsRedirectURI("https://website.com"))
+	assert.True(t, app.ContainsRedirectURI("https://webSITE.com"))  // ascii uppercase I
+	assert.False(t, app.ContainsRedirectURI("https://websİte.com")) // U+0130 as I, Latin Capital Letter I with Dot Above
+}
+
 func TestOAuth2Application_ValidateClientSecret(t *testing.T) {
 	require.NoError(t, unittest.PrepareTestDatabase())
 	app := unittest.AssertExistsAndLoadBean(t, &auth_model.OAuth2Application{ID: 1})
@@ -147,9 +154,18 @@ func TestGetOAuth2GrantByID(t *testing.T) {
 func TestOAuth2Grant_IncreaseCounter(t *testing.T) {
 	require.NoError(t, unittest.PrepareTestDatabase())
 	grant := unittest.AssertExistsAndLoadBean(t, &auth_model.OAuth2Grant{ID: 1, Counter: 1})
+
+	// First increment succeeds
 	require.NoError(t, grant.IncreaseCounter(db.DefaultContext))
 	assert.Equal(t, int64(2), grant.Counter)
 	unittest.AssertExistsAndLoadBean(t, &auth_model.OAuth2Grant{ID: 1, Counter: 2})
+
+	// Simulate a stale grant (counter still 1): must fail (concurrent replay)
+	grant.Counter = 1
+	require.Error(t, grant.IncreaseCounter(db.DefaultContext), "stale counter must be rejected")
+
+	// Counter in DB should be unchanged
+	unittest.AssertExistsAndLoadBean(t, &auth_model.OAuth2Grant{ID: 1, Counter: 2})
 }
 
 func TestOAuth2Grant_ScopeContains(t *testing.T) {
@@ -232,12 +248,33 @@ func TestOAuth2AuthorizationCode_ValidateCodeChallenge(t *testing.T) {
 	}
 	assert.False(t, code.ValidateCodeChallenge("foiwgjioriogeiogjerger"))
 
-	// test no code challenge
+	// test no PKCE at all (no challenge set, no verifier needed)
+	code = &auth_model.OAuth2AuthorizationCode{
+		CodeChallengeMethod: "",
+		CodeChallenge:       "",
+	}
+	assert.True(t, code.ValidateCodeChallenge(""))
+
+	// test PKCE required: challenge was set but verifier is empty
+	code = &auth_model.OAuth2AuthorizationCode{
+		CodeChallengeMethod: "S256",
+		CodeChallenge:       "CjvyTLSdR47G5zYenDA-eDWW4lRrO8yvjcWwbD_deOg",
+	}
+	assert.False(t, code.ValidateCodeChallenge(""), "PKCE required: S256 challenge set but empty verifier must be rejected")
+
+	code = &auth_model.OAuth2AuthorizationCode{
+		CodeChallengeMethod: "plain",
+		CodeChallenge:       "test123",
+	}
+	assert.False(t, code.ValidateCodeChallenge(""), "PKCE required: plain challenge set but empty verifier must be rejected")
+
+	// test challenge stored but method empty (malformed: should reject)
 	code = &auth_model.OAuth2AuthorizationCode{
 		CodeChallengeMethod: "",
 		CodeChallenge:       "foierjiogerogerg",
 	}
-	assert.True(t, code.ValidateCodeChallenge(""))
+	assert.False(t, code.ValidateCodeChallenge(""), "challenge present with empty method must be rejected")
+	assert.False(t, code.ValidateCodeChallenge("foierjiogerogerg"), "challenge present with empty method must be rejected even with matching verifier")
 }
 
 func TestOAuth2AuthorizationCode_GenerateRedirectURI(t *testing.T) {
@@ -262,6 +299,20 @@ func TestOAuth2AuthorizationCode_Invalidate(t *testing.T) {
 	unittest.AssertNotExistsBean(t, &auth_model.OAuth2AuthorizationCode{Code: "authcode"})
 }
 
+func TestOAuth2AuthorizationCode_Invalidate_DoubleUse(t *testing.T) {
+	require.NoError(t, unittest.PrepareTestDatabase())
+	code := unittest.AssertExistsAndLoadBean(t, &auth_model.OAuth2AuthorizationCode{Code: "authcode"})
+
+	// First invalidation should succeed
+	require.NoError(t, code.Invalidate(db.DefaultContext))
+	unittest.AssertNotExistsBean(t, &auth_model.OAuth2AuthorizationCode{Code: "authcode"})
+
+	// Second invalidation of the same code must fail (replay prevention)
+	err := code.Invalidate(db.DefaultContext)
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), "authorization code already used")
+}
+
 func TestOAuth2AuthorizationCode_TableName(t *testing.T) {
 	assert.Equal(t, "oauth2_authorization_code", new(auth_model.OAuth2AuthorizationCode).TableName())
 }
diff --git a/release-notes/12494.md b/release-notes/12494.md
new file mode 100644
index 0000000000..a26776b47c
--- /dev/null
+++ b/release-notes/12494.md
@@ -0,0 +1,6 @@
+- fix: prevent git write to wiki repo from unauthorized user via git HTTP
+- fix: prevent LFS authorization token from being used for read/write access after user's access is restricted from Forgejo
+- fix: prevent scoped API access (OAuth tokens, Access tokens) from accessing resources beyond their permitted scope via non-API endpoints (e.g. /user/repo/raw/...)
+- fix: implementing missing OAuth validation checks, improve protections against race conditions
+- fix: prevent OAuth redirect URI spoofing via non-ascii case collision
+- fix: strengthen Actions Artifact V4 signature algorithm against spoofing attacks
diff --git a/release-notes/12495.md b/release-notes/12495.md
new file mode 100644
index 0000000000..a26776b47c
--- /dev/null
+++ b/release-notes/12495.md
@@ -0,0 +1,6 @@
+- fix: prevent git write to wiki repo from unauthorized user via git HTTP
+- fix: prevent LFS authorization token from being used for read/write access after user's access is restricted from Forgejo
+- fix: prevent scoped API access (OAuth tokens, Access tokens) from accessing resources beyond their permitted scope via non-API endpoints (e.g. /user/repo/raw/...)
+- fix: implementing missing OAuth validation checks, improve protections against race conditions
+- fix: prevent OAuth redirect URI spoofing via non-ascii case collision
+- fix: strengthen Actions Artifact V4 signature algorithm against spoofing attacks
diff --git a/routers/api/actions/artifactsv4.go b/routers/api/actions/artifactsv4.go
index 56fe5cb2cc..c3d3c37e79 100644
--- a/routers/api/actions/artifactsv4.go
+++ b/routers/api/actions/artifactsv4.go
@@ -89,6 +89,7 @@ import (
 	"crypto/hmac"
 	"crypto/sha256"
 	"encoding/base64"
+	"encoding/binary"
 	"encoding/xml"
 	"fmt"
 	"io"
@@ -163,11 +164,20 @@ func ArtifactsV4Routes(prefix string) *web.Route {
 
 func (r artifactV4Routes) buildSignature(endp, expires, artifactName string, taskID, artifactID int64) []byte {
 	mac := hmac.New(sha256.New, setting.GetGeneralTokenSigningSecret())
+	// For each string field, write the length of the string first to prevent user-controlled strings from bleeding into
+	// each other and causing a signature match when it isn't expected.
+	_ = binary.Write(mac, binary.BigEndian, int64(len(endp)))
 	mac.Write([]byte(endp))
+	_ = binary.Write(mac, binary.BigEndian, int64(len(expires)))
 	mac.Write([]byte(expires))
+	_ = binary.Write(mac, binary.BigEndian, int64(len(artifactName)))
 	mac.Write([]byte(artifactName))
-	fmt.Fprint(mac, taskID)
-	fmt.Fprint(mac, artifactID)
+
+	// Write TaskID & ArtifactID as binary values to prevent them from bleeding together; eg. TaskID="2" &
+	// ArtifactID="18" could look the same in the signature as TaskID="21" and ArtifactID="8" if they're written as
+	// strings.
+	_ = binary.Write(mac, binary.BigEndian, taskID)
+	_ = binary.Write(mac, binary.BigEndian, artifactID)
 	return mac.Sum(nil)
 }
 
diff --git a/routers/web/auth/oauth.go b/routers/web/auth/oauth.go
index 914e181259..828027c0a8 100644
--- a/routers/web/auth/oauth.go
+++ b/routers/web/auth/oauth.go
@@ -803,6 +803,16 @@ func handleRefreshToken(ctx *context.Context, form forms.AccessTokenForm, server
 		return
 	}
 
+	// Ensure the refresh token's grant belongs to the requesting client.
+	// This prevents cross-client token usage (RFC 6749 Section 10.4).
+	if grant.ApplicationID != app.ID {
+		handleAccessTokenError(ctx, AccessTokenErrorResponse{
+			ErrorCode:        AccessTokenErrorCodeInvalidGrant,
+			ErrorDescription: "refresh token was not issued to this client",
+		})
+		return
+	}
+
 	// check if token got already used
 	if setting.OAuth2.InvalidateRefreshTokens && (grant.Counter != token.Counter || token.Counter == 0) {
 		handleAccessTokenError(ctx, AccessTokenErrorResponse{
@@ -863,6 +873,15 @@ func handleAuthorizationCode(ctx *context.Context, form forms.AccessTokenForm, s
 		})
 		return
 	}
+	// Per RFC 6749 §4.1.3, if redirect_uri was included in the authorization request,
+	// it MUST be identical to the value included in the token request.
+	if authorizationCode.RedirectURI != "" && form.RedirectURI != authorizationCode.RedirectURI {
+		handleAccessTokenError(ctx, AccessTokenErrorResponse{
+			ErrorCode:        AccessTokenErrorCodeUnauthorizedClient,
+			ErrorDescription: "redirect_uri does not match the authorization request",
+		})
+		return
+	}
 	// check if granted for this application
 	if authorizationCode.Grant.ApplicationID != app.ID {
 		handleAccessTokenError(ctx, AccessTokenErrorResponse{
@@ -877,6 +896,7 @@ func handleAuthorizationCode(ctx *context.Context, form forms.AccessTokenForm, s
 			ErrorCode:        AccessTokenErrorCodeInvalidRequest,
 			ErrorDescription: "cannot proceed your request",
 		})
+		return
 	}
 	resp, tokenErr := newAccessTokenResponse(ctx, authorizationCode.Grant, serverKey, clientKey)
 	if tokenErr != nil {
diff --git a/routers/web/repo/attachment.go b/routers/web/repo/attachment.go
index 5497738f0b..65be51ba08 100644
--- a/routers/web/repo/attachment.go
+++ b/routers/web/repo/attachment.go
@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"net/http"
 
+	"forgejo.org/models/auth"
 	access_model "forgejo.org/models/perm/access"
 	repo_model "forgejo.org/models/repo"
 	"forgejo.org/modules/httpcache"
@@ -98,6 +99,30 @@ func ServeAttachment(ctx *context.Context, uuid string) {
 		return
 	}
 
+	// Some paths like `/attachment/{uuid}` can be accessed with API authentication mechanisms, which can have limited
+	// scopes (eg. user access tokens, OAuth grants).  There's no middleware on these routes that enforce API scopes
+	// because (a) they're not API endpoints, and (b) the scoped required is dependant on the attachment.
+	if hasScope, scope := ctx.Authentication.Scope().Get(); hasScope {
+		var requiredScope auth.AccessTokenScope
+		if attach.ReleaseID != 0 {
+			requiredScope = auth.AccessTokenScopeReadRepository
+		} else if attach.IssueID != 0 {
+			requiredScope = auth.AccessTokenScopeReadIssue
+		} else {
+			ctx.ServerError("UnidentifiedAttachmentResource", fmt.Errorf("unable to identify resource for attachment id=%d", attach.ID))
+			return
+		}
+		allow, err := scope.HasScope(requiredScope)
+		if err != nil {
+			ctx.ServerError("checking scope failed", err)
+			return
+		}
+		if !allow {
+			ctx.Error(http.StatusForbidden, "scopedAccessCheck", fmt.Sprintf("token does not have at least one of required scope(s): %v", requiredScope))
+			return
+		}
+	}
+
 	repository, unitType, err := repo_service.LinkedRepository(ctx, attach)
 	if err != nil {
 		ctx.ServerError("LinkedRepository", err)
@@ -110,7 +135,16 @@ func ServeAttachment(ctx *context.Context, uuid string) {
 			return
 		}
 	} else { // If we have the repository we check access
-		perm, err := access_model.GetUserRepoPermission(ctx, repository, ctx.Doer)
+		// Some paths like `/attachment/{uuid}` can be accessed with API authentication mechanisms, and therefore *may*
+		// have AuthorizationReducers that need to be enforced:
+		reducer := ctx.Authentication.Reducer()
+		var perm access_model.Permission
+		var err error
+		if reducer != nil {
+			perm, err = access_model.GetUserRepoPermissionWithReducer(ctx, repository, ctx.Doer, reducer)
+		} else {
+			perm, err = access_model.GetUserRepoPermission(ctx, repository, ctx.Doer)
+		}
 		if err != nil {
 			ctx.Error(http.StatusInternalServerError, "GetUserRepoPermission", err.Error())
 			return
diff --git a/routers/web/repo/githttp.go b/routers/web/repo/githttp.go
index 936b108281..6703676745 100644
--- a/routers/web/repo/githttp.go
+++ b/routers/web/repo/githttp.go
@@ -184,8 +184,10 @@ func httpBase(ctx *context.Context) *serviceHandler {
 		}
 
 		if repoExist {
-			// Because of special ref "refs/for" .. , need delay write permission check
-			accessMode = perm.AccessModeRead
+			if !isWiki {
+				// Because of special ref "refs/for" .. , need delay write permission check
+				accessMode = perm.AccessModeRead
+			}
 
 			if hasTaskID, taskID := ctx.Authentication.ActionsTaskID().Get(); hasTaskID {
 				task, err := actions_model.GetTaskByID(ctx, taskID)
diff --git a/services/context/permission.go b/services/context/permission.go
index 44adbbd6d9..ad6843b440 100644
--- a/services/context/permission.go
+++ b/services/context/permission.go
@@ -4,6 +4,7 @@
 package context
 
 import (
+	"fmt"
 	"net/http"
 	"slices"
 
@@ -57,6 +58,23 @@ func RequireRepoWriterOr(unitTypes ...unit.Type) func(ctx *Context) {
 // RequireRepoReader returns a middleware for requiring repository read to the specify unitType
 func RequireRepoReader(unitType unit.Type) func(ctx *Context) {
 	return func(ctx *Context) {
+		// Typically checks for authentication scopes won't be relevant for non-API requests where this middleware is
+		// used; but, some paths like `/user/repo/raw/...` can be accessed with API authentication mechanisms.  In those
+		// edge cases, check that `read:repository` scope is present if the authentication method indicates a limited
+		// scope.
+		hasScope, scope := ctx.Authentication.Scope().Get()
+		if hasScope {
+			allow, err := scope.HasScope(auth_model.AccessTokenScopeReadRepository)
+			if err != nil {
+				ctx.ServerError("checking scope failed", err)
+				return
+			}
+			if !allow {
+				ctx.Error(http.StatusForbidden, "scopedAccessCheck", fmt.Sprintf("token does not have at least one of required scope(s): %v", auth_model.AccessTokenScopeReadRepository))
+				return
+			}
+		}
+
 		if !ctx.Repo.CanRead(unitType) {
 			if log.IsTrace() {
 				if ctx.IsSigned {
diff --git a/services/context/repo.go b/services/context/repo.go
index 583eb35474..f39b6d342d 100644
--- a/services/context/repo.go
+++ b/services/context/repo.go
@@ -375,7 +375,15 @@ func repoAssignment(ctx *Context, repo *repo_model.Repository) {
 		return
 	}
 
-	ctx.Repo.Permission, err = access_model.GetUserRepoPermission(ctx, repo, ctx.Doer)
+	// Typically checks for authorization reducers won't be relevant for non-API requests where this middleware is used;
+	// but, some paths like `/user/repo/raw/...` can be accessed with API authentication mechanisms.  In those edge
+	// cases, initialize `ctx.Repo.Permission` based upon the reduced permission set available.
+	authorizationReducer := ctx.Authentication.Reducer()
+	if authorizationReducer == nil {
+		ctx.Repo.Permission, err = access_model.GetUserRepoPermission(ctx, repo, ctx.Doer)
+	} else {
+		ctx.Repo.Permission, err = access_model.GetUserRepoPermissionWithReducer(ctx, repo, ctx.Doer, authorizationReducer)
+	}
 	if err != nil {
 		ctx.ServerError("GetUserRepoPermission", err)
 		return
diff --git a/services/lfs/server.go b/services/lfs/server.go
index 457602243e..1dfd58a3c0 100644
--- a/services/lfs/server.go
+++ b/services/lfs/server.go
@@ -607,6 +607,20 @@ func handleLFSToken(ctx stdCtx.Context, tokenSHA string, target *repo_model.Repo
 		log.Error("Unable to GetUserById[%d]: Error: %v", claims.UserID, err)
 		return nil, err
 	}
+
+	if !u.IsAccessAllowed(ctx) {
+		return nil, errors.New("user access is blocked")
+	}
+
+	repoPerm, err := access_model.GetUserRepoPermission(ctx, target, u)
+	if err != nil {
+		log.Error("Unable to GetUserRepoPermission[%d]: Error: %v", claims.UserID, err)
+		return nil, err
+	}
+	if !repoPerm.CanAccess(mode, unit.TypeCode) {
+		return nil, errors.New("user does not have access to the repository")
+	}
+
 	return u, nil
 }
 
diff --git a/services/lfs/server_test.go b/services/lfs/server_test.go
index 065387ce08..875a99603e 100644
--- a/services/lfs/server_test.go
+++ b/services/lfs/server_test.go
@@ -78,6 +78,75 @@ func testAuthenticate(t *testing.T, cfg string) {
 		assert.EqualValues(t, 2, u.ID)
 	})
 
+	t.Run("handleLFSToken nonexistent user", func(t *testing.T) {
+		tokenMissing, _ := getLFSAuthTokenWithBearer(authTokenOptions{Op: "download", UserID: 999, RepoID: 1})
+		_, tokenMissing, _ = strings.Cut(tokenMissing, " ")
+
+		u, err := handleLFSToken(ctx, tokenMissing, repo1, perm_model.AccessModeRead)
+		require.Error(t, err)
+		assert.Contains(t, err.Error(), "user does not exist")
+		assert.Nil(t, u)
+	})
+
+	t.Run("handleLFSToken nonexistent repo", func(t *testing.T) {
+		tokenBadRepo, _ := getLFSAuthTokenWithBearer(authTokenOptions{Op: "download", UserID: 2, RepoID: 999})
+		_, tokenBadRepo, _ = strings.Cut(tokenBadRepo, " ")
+		badRepo := &repo_model.Repository{ID: 999}
+
+		u, err := handleLFSToken(ctx, tokenBadRepo, badRepo, perm_model.AccessModeRead)
+		require.Error(t, err)
+		assert.Nil(t, u)
+	})
+
+	t.Run("handleLFSToken blocked user", func(t *testing.T) {
+		tokenBlocked, _ := getLFSAuthTokenWithBearer(authTokenOptions{Op: "download", UserID: 37, RepoID: 1})
+		_, tokenBlocked, _ = strings.Cut(tokenBlocked, " ")
+
+		u, err := handleLFSToken(ctx, tokenBlocked, repo1, perm_model.AccessModeRead)
+		require.Error(t, err)
+		assert.Contains(t, err.Error(), "user access is blocked")
+		assert.Nil(t, u)
+	})
+
+	t.Run("handleLFSToken no repo access", func(t *testing.T) {
+		repo2 := unittest.AssertExistsAndLoadBean(t, &repo_model.Repository{ID: 2})
+		tokenNoAccess, _ := getLFSAuthTokenWithBearer(authTokenOptions{Op: "download", UserID: 10, RepoID: 2})
+		_, tokenNoAccess, _ = strings.Cut(tokenNoAccess, " ")
+
+		u, err := handleLFSToken(ctx, tokenNoAccess, repo2, perm_model.AccessModeRead)
+		require.Error(t, err)
+		assert.Contains(t, err.Error(), "does not have access to the repository")
+		assert.Nil(t, u)
+	})
+
+	t.Run("handleLFSToken upload write access allowed", func(t *testing.T) {
+		tokenUploadRW, _ := getLFSAuthTokenWithBearer(authTokenOptions{Op: "upload", UserID: 2, RepoID: 1})
+		_, tokenUploadRW, _ = strings.Cut(tokenUploadRW, " ")
+
+		u, err := handleLFSToken(ctx, tokenUploadRW, repo1, perm_model.AccessModeWrite)
+		require.NoError(t, err)
+		assert.EqualValues(t, 2, u.ID)
+	})
+
+	t.Run("handleLFSToken upload read-only access denied", func(t *testing.T) {
+		tokenUploadRO, _ := getLFSAuthTokenWithBearer(authTokenOptions{Op: "upload", UserID: 10, RepoID: 1})
+		_, tokenUploadRO, _ = strings.Cut(tokenUploadRO, " ")
+
+		u, err := handleLFSToken(ctx, tokenUploadRO, repo1, perm_model.AccessModeWrite)
+		require.Error(t, err)
+		assert.Contains(t, err.Error(), "does not have access to the repository")
+		assert.Nil(t, u)
+	})
+
+	t.Run("handleLFSToken download read-only access allowed", func(t *testing.T) {
+		tokenDownloadRO, _ := getLFSAuthTokenWithBearer(authTokenOptions{Op: "download", UserID: 10, RepoID: 1})
+		_, tokenDownloadRO, _ = strings.Cut(tokenDownloadRO, " ")
+
+		u, err := handleLFSToken(ctx, tokenDownloadRO, repo1, perm_model.AccessModeRead)
+		require.NoError(t, err)
+		assert.EqualValues(t, 10, u.ID)
+	})
+
 	t.Run("authenticate", func(t *testing.T) {
 		const prefixBearer = "Bearer "
 		assert.False(t, authenticate(ctx, repo1, "", true, false))
diff --git a/tests/integration/attachment_test.go b/tests/integration/attachment_test.go
index 4e29407c2a..06c1bb82ca 100644
--- a/tests/integration/attachment_test.go
+++ b/tests/integration/attachment_test.go
@@ -13,9 +13,13 @@ import (
 	"strings"
 	"testing"
 
+	auth_model "forgejo.org/models/auth"
 	repo_model "forgejo.org/models/repo"
+	unit_model "forgejo.org/models/unit"
+	"forgejo.org/models/unittest"
 	"forgejo.org/modules/storage"
 	"forgejo.org/modules/test"
+	repo_service "forgejo.org/services/repository"
 	"forgejo.org/tests"
 
 	"github.com/stretchr/testify/assert"
@@ -131,3 +135,226 @@ func TestGetAttachment(t *testing.T) {
 		})
 	}
 }
+
+// Access under `/attachments/{uuid}` and `/{user}/{repo}/attachments/{uuid}` is permitted for API tokens.  Those API
+// tokens then need to have the read:issue or read:repository and the correct resource scopes to permit access, though.
+func TestGetAttachmentViaAPITokens(t *testing.T) {
+	defer unittest.OverrideFixtures("tests/integration/fixtures/TestGetAttachmentViaAPITokens")()
+	defer tests.PrepareTestEnv(t)()
+
+	// Create attachment data for an attachment added by this test's fixture.
+	_, err := storage.Attachments.Save(repo_model.AttachmentRelativePath("d962b49e-e32a-4b72-922d-33b551b629e2"), strings.NewReader("hello universe"), -1)
+	require.NoError(t, err)
+
+	// Enable Issues unit on repo 16, one of our test targets.
+	repo_service.UpdateRepositoryUnits(t.Context(),
+		unittest.AssertExistsAndLoadBean(t, &repo_model.Repository{ID: 16}),
+		[]repo_model.RepoUnit{{
+			RepoID: 16,
+			Type:   unit_model.TypeIssues,
+		}}, nil)
+
+	t.Run("attachments", func(t *testing.T) {
+		t.Run("no read:issue scope", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+
+			session := loginUser(t, "user2")
+			allToken := getTokenForLoggedInUser(t, session, auth_model.AccessTokenScopeReadMisc)
+
+			t.Run("denied public repo1", func(t *testing.T) {
+				defer tests.PrintCurrentTest(t)()
+				req := NewRequest(t, "GET", "/attachments/a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11").AddTokenAuth(allToken)
+				MakeRequest(t, req, http.StatusForbidden)
+			})
+			t.Run("denied private repo2", func(t *testing.T) {
+				defer tests.PrintCurrentTest(t)()
+				req := NewRequest(t, "GET", "/attachments/a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a12").AddTokenAuth(allToken)
+				MakeRequest(t, req, http.StatusForbidden)
+			})
+			// repo16 is a second repo used in fine-grain testing below, so we include it in other tests as a baseline
+			t.Run("denied private repo16", func(t *testing.T) {
+				defer tests.PrintCurrentTest(t)()
+				req := NewRequest(t, "GET", "/attachments/d962b49e-e32a-4b72-922d-33b551b629e2").AddTokenAuth(allToken)
+				MakeRequest(t, req, http.StatusForbidden)
+			})
+		})
+
+		t.Run("all access token", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+
+			session := loginUser(t, "user2")
+			allToken := getTokenForLoggedInUser(t, session, auth_model.AccessTokenScopeReadIssue)
+
+			t.Run("allowed public repo1", func(t *testing.T) {
+				defer tests.PrintCurrentTest(t)()
+				req := NewRequest(t, "GET", "/attachments/a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11").AddTokenAuth(allToken)
+				resp := MakeRequest(t, req, http.StatusOK)
+				assert.Equal(t, "hello world", resp.Body.String())
+			})
+			t.Run("allowed private repo2", func(t *testing.T) {
+				defer tests.PrintCurrentTest(t)()
+				req := NewRequest(t, "GET", "/attachments/a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a12").AddTokenAuth(allToken)
+				resp := MakeRequest(t, req, http.StatusOK)
+				assert.Equal(t, "hello world", resp.Body.String())
+			})
+			// repo16 is a second repo used in fine-grain testing below, so we include it in other tests as a baseline
+			t.Run("allowed private repo16", func(t *testing.T) {
+				defer tests.PrintCurrentTest(t)()
+				req := NewRequest(t, "GET", "/attachments/d962b49e-e32a-4b72-922d-33b551b629e2").AddTokenAuth(allToken)
+				resp := MakeRequest(t, req, http.StatusOK)
+				assert.Equal(t, "hello universe", resp.Body.String())
+			})
+		})
+
+		t.Run("public-only access token", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+			session := loginUser(t, "user2")
+			publicOnlyToken := getTokenForLoggedInUser(t, session, auth_model.AccessTokenScopePublicOnly, auth_model.AccessTokenScopeReadIssue)
+
+			t.Run("allowed public repo1", func(t *testing.T) {
+				defer tests.PrintCurrentTest(t)()
+				req := NewRequest(t, "GET", "/attachments/a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11").AddTokenAuth(publicOnlyToken)
+				resp := MakeRequest(t, req, http.StatusOK)
+				assert.Equal(t, "hello world", resp.Body.String())
+			})
+			t.Run("denied private repo2", func(t *testing.T) {
+				defer tests.PrintCurrentTest(t)()
+				req := NewRequest(t, "GET", "/attachments/a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a12").AddTokenAuth(publicOnlyToken)
+				MakeRequest(t, req, http.StatusNotFound)
+			})
+			t.Run("denied private repo16", func(t *testing.T) {
+				defer tests.PrintCurrentTest(t)()
+				req := NewRequest(t, "GET", "/attachments/d962b49e-e32a-4b72-922d-33b551b629e2").AddTokenAuth(publicOnlyToken)
+				MakeRequest(t, req, http.StatusNotFound)
+			})
+		})
+
+		t.Run("specific repo access token", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+			repo2OnlyToken := createFineGrainedRepoAccessToken(t, "user2",
+				[]auth_model.AccessTokenScope{auth_model.AccessTokenScopeReadIssue},
+				[]int64{2},
+			)
+
+			t.Run("allowed public repo1", func(t *testing.T) {
+				defer tests.PrintCurrentTest(t)()
+				req := NewRequest(t, "GET", "/attachments/a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11").AddTokenAuth(repo2OnlyToken)
+				resp := MakeRequest(t, req, http.StatusOK)
+				assert.Equal(t, "hello world", resp.Body.String())
+			})
+			t.Run("allowed inside fine-grain repo2", func(t *testing.T) {
+				defer tests.PrintCurrentTest(t)()
+				req := NewRequest(t, "GET", "/attachments/a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a12").AddTokenAuth(repo2OnlyToken)
+				resp := MakeRequest(t, req, http.StatusOK)
+				assert.Equal(t, "hello world", resp.Body.String())
+			})
+			t.Run("denied private outside fine-grain repo16", func(t *testing.T) {
+				defer tests.PrintCurrentTest(t)()
+				req := NewRequest(t, "GET", "/attachments/d962b49e-e32a-4b72-922d-33b551b629e2").AddTokenAuth(repo2OnlyToken)
+				MakeRequest(t, req, http.StatusNotFound)
+			})
+		})
+	})
+
+	t.Run("user-repo-attachments", func(t *testing.T) {
+		t.Run("no read:issue scope", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+
+			session := loginUser(t, "user2")
+			allToken := getTokenForLoggedInUser(t, session, auth_model.AccessTokenScopeReadMisc)
+
+			t.Run("denied public repo1", func(t *testing.T) {
+				defer tests.PrintCurrentTest(t)()
+				req := NewRequest(t, "GET", "/user2/repo1/attachments/a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11").AddTokenAuth(allToken)
+				MakeRequest(t, req, http.StatusForbidden)
+			})
+			t.Run("denied private repo2", func(t *testing.T) {
+				defer tests.PrintCurrentTest(t)()
+				req := NewRequest(t, "GET", "/user2/repo2/attachments/a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a12").AddTokenAuth(allToken)
+				MakeRequest(t, req, http.StatusForbidden)
+			})
+			// repo16 is a second repo used in fine-grain testing below, so we include it in other tests as a baseline
+			t.Run("denied private repo16", func(t *testing.T) {
+				defer tests.PrintCurrentTest(t)()
+				req := NewRequest(t, "GET", "/user2/repo16/attachments/d962b49e-e32a-4b72-922d-33b551b629e2").AddTokenAuth(allToken)
+				MakeRequest(t, req, http.StatusForbidden)
+			})
+		})
+
+		t.Run("all access token", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+
+			session := loginUser(t, "user2")
+			allToken := getTokenForLoggedInUser(t, session, auth_model.AccessTokenScopeReadIssue)
+
+			t.Run("allowed public repo1", func(t *testing.T) {
+				defer tests.PrintCurrentTest(t)()
+				req := NewRequest(t, "GET", "/user2/repo1/attachments/a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11").AddTokenAuth(allToken)
+				resp := MakeRequest(t, req, http.StatusOK)
+				assert.Equal(t, "hello world", resp.Body.String())
+			})
+			t.Run("allowed private repo2", func(t *testing.T) {
+				defer tests.PrintCurrentTest(t)()
+				req := NewRequest(t, "GET", "/user2/repo2/attachments/a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a12").AddTokenAuth(allToken)
+				resp := MakeRequest(t, req, http.StatusOK)
+				assert.Equal(t, "hello world", resp.Body.String())
+			})
+			// repo16 is a second repo used in fine-grain testing below, so we include it in other tests as a baseline
+			t.Run("allowed private repo16", func(t *testing.T) {
+				defer tests.PrintCurrentTest(t)()
+				req := NewRequest(t, "GET", "/user2/repo16/attachments/d962b49e-e32a-4b72-922d-33b551b629e2").AddTokenAuth(allToken)
+				resp := MakeRequest(t, req, http.StatusOK)
+				assert.Equal(t, "hello universe", resp.Body.String())
+			})
+		})
+
+		t.Run("public-only access token", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+			session := loginUser(t, "user2")
+			publicOnlyToken := getTokenForLoggedInUser(t, session, auth_model.AccessTokenScopePublicOnly, auth_model.AccessTokenScopeReadIssue)
+
+			t.Run("allowed public repo1", func(t *testing.T) {
+				defer tests.PrintCurrentTest(t)()
+				req := NewRequest(t, "GET", "/user2/repo1/attachments/a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11").AddTokenAuth(publicOnlyToken)
+				resp := MakeRequest(t, req, http.StatusOK)
+				assert.Equal(t, "hello world", resp.Body.String())
+			})
+			t.Run("denied private repo2", func(t *testing.T) {
+				defer tests.PrintCurrentTest(t)()
+				req := NewRequest(t, "GET", "/user2/repo2/attachments/a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a12").AddTokenAuth(publicOnlyToken)
+				MakeRequest(t, req, http.StatusNotFound)
+			})
+			t.Run("denied private repo16", func(t *testing.T) {
+				defer tests.PrintCurrentTest(t)()
+				req := NewRequest(t, "GET", "/user2/repo16/attachments/d962b49e-e32a-4b72-922d-33b551b629e2").AddTokenAuth(publicOnlyToken)
+				MakeRequest(t, req, http.StatusNotFound)
+			})
+		})
+
+		t.Run("specific repo access token", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+			repo2OnlyToken := createFineGrainedRepoAccessToken(t, "user2",
+				[]auth_model.AccessTokenScope{auth_model.AccessTokenScopeReadIssue},
+				[]int64{2},
+			)
+
+			t.Run("allowed public repo1", func(t *testing.T) {
+				defer tests.PrintCurrentTest(t)()
+				req := NewRequest(t, "GET", "/user2/repo1/attachments/a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11").AddTokenAuth(repo2OnlyToken)
+				resp := MakeRequest(t, req, http.StatusOK)
+				assert.Equal(t, "hello world", resp.Body.String())
+			})
+			t.Run("allowed inside fine-grain repo2", func(t *testing.T) {
+				defer tests.PrintCurrentTest(t)()
+				req := NewRequest(t, "GET", "/user2/repo2/attachments/a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a12").AddTokenAuth(repo2OnlyToken)
+				resp := MakeRequest(t, req, http.StatusOK)
+				assert.Equal(t, "hello world", resp.Body.String())
+			})
+			t.Run("denied private outside fine-grain repo16", func(t *testing.T) {
+				defer tests.PrintCurrentTest(t)()
+				req := NewRequest(t, "GET", "/user2/repo16/attachments/d962b49e-e32a-4b72-922d-33b551b629e2").AddTokenAuth(repo2OnlyToken)
+				MakeRequest(t, req, http.StatusNotFound)
+			})
+		})
+	})
+}
diff --git a/tests/integration/download_test.go b/tests/integration/download_test.go
index d5e68402c5..70acc7f16f 100644
--- a/tests/integration/download_test.go
+++ b/tests/integration/download_test.go
@@ -7,6 +7,7 @@ import (
 	"net/http"
 	"testing"
 
+	auth_model "forgejo.org/models/auth"
 	"forgejo.org/modules/setting"
 	"forgejo.org/tests"
 
@@ -15,7 +16,6 @@ import (
 
 func TestDownloadByID(t *testing.T) {
 	defer tests.PrepareTestEnv(t)()
-
 	session := loginUser(t, "user2")
 
 	// Request raw blob
@@ -91,3 +91,110 @@ func TestDownloadRawTextFileWithMimeTypeMapping(t *testing.T) {
 	delete(setting.MimeTypeMap.Map, ".xml")
 	setting.MimeTypeMap.Enabled = false
 }
+
+// Access under `/raw` is permitted for API tokens.  Those API tokens then need to have the read:repository and the
+// correct resource scopes to permit access, though.  The below series of tests covers the middleware combinations on
+// the entire `/user/repo/raw/*` URL tree as they use a common middleware implementation.
+func TestDownloadAccessViaAPITokens(t *testing.T) {
+	defer tests.PrepareTestEnv(t)()
+
+	t.Run("no read:repository scope", func(t *testing.T) {
+		defer tests.PrintCurrentTest(t)()
+
+		session := loginUser(t, "user2")
+		allToken := getTokenForLoggedInUser(t, session, auth_model.AccessTokenScopeReadMisc)
+
+		t.Run("denied public repo1", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+			req := NewRequest(t, "GET", "/user2/repo1/raw/blob/4b4851ad51df6a7d9f25c979345979eaeb5b349f").AddTokenAuth(allToken)
+			MakeRequest(t, req, http.StatusForbidden)
+		})
+		t.Run("denied private repo2", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+			req := NewRequest(t, "GET", "/user2/repo2/raw/blob/1032bbf17fbc0d9c95bb5418dabe8f8c99278700").AddTokenAuth(allToken)
+			MakeRequest(t, req, http.StatusForbidden)
+		})
+		// repo16 is a second repo used in fine-grain testing below, so we include it in other tests as a baseline
+		t.Run("denied private repo16", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+			req := NewRequest(t, "GET", "/user2/repo16/raw/blob/69554a64c1e6030f051e5c3f94bfbd773cd6a324").AddTokenAuth(allToken)
+			MakeRequest(t, req, http.StatusForbidden)
+		})
+	})
+
+	t.Run("all access token", func(t *testing.T) {
+		defer tests.PrintCurrentTest(t)()
+
+		session := loginUser(t, "user2")
+		allToken := getTokenForLoggedInUser(t, session, auth_model.AccessTokenScopeReadRepository)
+
+		t.Run("allowed public repo1", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+			req := NewRequest(t, "GET", "/user2/repo1/raw/blob/4b4851ad51df6a7d9f25c979345979eaeb5b349f").AddTokenAuth(allToken)
+			resp := MakeRequest(t, req, http.StatusOK)
+			assert.Equal(t, "# repo1\n\nDescription for repo1", resp.Body.String())
+		})
+		t.Run("allowed private repo2", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+			req := NewRequest(t, "GET", "/user2/repo2/raw/blob/1032bbf17fbc0d9c95bb5418dabe8f8c99278700").AddTokenAuth(allToken)
+			resp := MakeRequest(t, req, http.StatusOK)
+			assert.Equal(t, "tree ba1aed4e2ea2443d76cec241b96be4ec990852ec\nparent 205ac761f3326a7ebe416e8673760016450b5cec\nauthor Jimmy Praet <jimmy.praet@telenet.be> 1624996449 +0200\ncommitter Jimmy Praet <jimmy.praet@telenet.be> 1624996449 +0200\n\nAdd test.xml\n", resp.Body.String())
+		})
+		// repo16 is a second repo used in fine-grain testing below, so we include it in other tests as a baseline
+		t.Run("allowed private repo16", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+			req := NewRequest(t, "GET", "/user2/repo16/raw/blob/69554a64c1e6030f051e5c3f94bfbd773cd6a324").AddTokenAuth(allToken)
+			resp := MakeRequest(t, req, http.StatusOK)
+			assert.Equal(t, "tree 24f83a471f77579fea57bac7255d6e64e70fce1c\nparent 27566bd5738fc8b4e3fef3c5e72cce608537bd95\nauthor User2 <user2@example.com> 1502042309 +0200\ncommitter User2 <user2@example.com> 1502042309 +0200\n\nnot signed commit\n", resp.Body.String())
+		})
+	})
+
+	t.Run("public-only access token", func(t *testing.T) {
+		defer tests.PrintCurrentTest(t)()
+		session := loginUser(t, "user2")
+		publicOnlyToken := getTokenForLoggedInUser(t, session, auth_model.AccessTokenScopePublicOnly, auth_model.AccessTokenScopeReadRepository)
+
+		t.Run("allowed public repo1", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+			req := NewRequest(t, "GET", "/user2/repo1/raw/blob/4b4851ad51df6a7d9f25c979345979eaeb5b349f").AddTokenAuth(publicOnlyToken)
+			resp := MakeRequest(t, req, http.StatusOK)
+			assert.Equal(t, "# repo1\n\nDescription for repo1", resp.Body.String())
+		})
+		t.Run("denied private repo2", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+			req := NewRequest(t, "GET", "/user2/repo2/raw/blob/1032bbf17fbc0d9c95bb5418dabe8f8c99278700").AddTokenAuth(publicOnlyToken)
+			MakeRequest(t, req, http.StatusNotFound)
+		})
+		t.Run("denied private repo16", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+			req := NewRequest(t, "GET", "/user2/repo16/raw/blob/69554a64c1e6030f051e5c3f94bfbd773cd6a324").AddTokenAuth(publicOnlyToken)
+			MakeRequest(t, req, http.StatusNotFound)
+		})
+	})
+
+	t.Run("specific repo access token", func(t *testing.T) {
+		defer tests.PrintCurrentTest(t)()
+		repo2OnlyToken := createFineGrainedRepoAccessToken(t, "user2",
+			[]auth_model.AccessTokenScope{auth_model.AccessTokenScopeReadRepository},
+			[]int64{2},
+		)
+
+		t.Run("allowed public repo1", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+			req := NewRequest(t, "GET", "/user2/repo1/raw/blob/4b4851ad51df6a7d9f25c979345979eaeb5b349f").AddTokenAuth(repo2OnlyToken)
+			resp := MakeRequest(t, req, http.StatusOK)
+			assert.Equal(t, "# repo1\n\nDescription for repo1", resp.Body.String())
+		})
+		t.Run("allowed inside fine-grain repo2", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+			req := NewRequest(t, "GET", "/user2/repo2/raw/blob/1032bbf17fbc0d9c95bb5418dabe8f8c99278700").AddTokenAuth(repo2OnlyToken)
+			resp := MakeRequest(t, req, http.StatusOK)
+			assert.Equal(t, "tree ba1aed4e2ea2443d76cec241b96be4ec990852ec\nparent 205ac761f3326a7ebe416e8673760016450b5cec\nauthor Jimmy Praet <jimmy.praet@telenet.be> 1624996449 +0200\ncommitter Jimmy Praet <jimmy.praet@telenet.be> 1624996449 +0200\n\nAdd test.xml\n", resp.Body.String())
+		})
+		t.Run("denied private outside fine-grain repo16", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+			req := NewRequest(t, "GET", "/user2/repo16/raw/blob/69554a64c1e6030f051e5c3f94bfbd773cd6a324").AddTokenAuth(repo2OnlyToken)
+			MakeRequest(t, req, http.StatusNotFound)
+		})
+	})
+}
diff --git a/tests/integration/fixtures/TestGetAttachmentViaAPITokens/attachment.yml b/tests/integration/fixtures/TestGetAttachmentViaAPITokens/attachment.yml
new file mode 100644
index 0000000000..334b33cefa
--- /dev/null
+++ b/tests/integration/fixtures/TestGetAttachmentViaAPITokens/attachment.yml
@@ -0,0 +1,12 @@
+-
+  id: 50
+  uuid: d962b49e-e32a-4b72-922d-33b551b629e2
+  repo_id: 16
+  issue_id: 50
+  release_id: 0
+  uploader_id: 0
+  comment_id: 0
+  name: attach1
+  download_count: 0
+  size: 0
+  created_unix: 946684800
diff --git a/tests/integration/fixtures/TestGetAttachmentViaAPITokens/issue.yml b/tests/integration/fixtures/TestGetAttachmentViaAPITokens/issue.yml
new file mode 100644
index 0000000000..7a876ef5b2
--- /dev/null
+++ b/tests/integration/fixtures/TestGetAttachmentViaAPITokens/issue.yml
@@ -0,0 +1,16 @@
+-
+  id: 50
+  repo_id: 16
+  index: 1
+  poster_id: 1
+  original_author_id: 0
+  name: issue1
+  content: content for the first issue
+  milestone_id: 0
+  priority: 0
+  is_closed: false
+  is_pull: false
+  num_comments: 3
+  created_unix: 946684800
+  updated_unix: 978307200
+  is_locked: false
diff --git a/tests/integration/oauth_test.go b/tests/integration/oauth_test.go
index 3f14324cf7..d87d725dbd 100644
--- a/tests/integration/oauth_test.go
+++ b/tests/integration/oauth_test.go
@@ -194,12 +194,45 @@ func TestAccessTokenExchange(t *testing.T) {
 	assert.Greater(t, len(parsed.RefreshToken), 10)
 }
 
+func TestAccessTokenExchangeRedirectURIMismatch(t *testing.T) {
+	defer tests.PrepareTestEnv(t)()
+
+	// The auth code fixture has redirect_uri="a", but we send a different
+	// URI that is registered with the app ("https://example.com/xyzzy").
+	// Per RFC 6749 §4.1.3, this must be rejected.
+	req := NewRequestWithValues(t, "POST", "/login/oauth/access_token", map[string]string{
+		"grant_type":    "authorization_code",
+		"client_id":     "da7da3ba-9a13-4167-856f-3899de0b0138",
+		"client_secret": "4MK8Na6R55smdCY0WuCCumZ6hjRPnGY5saWVRHHjJiA=",
+		"redirect_uri":  "https://example.com/xyzzy",
+		"code":          "authcode",
+		"code_verifier": "N1Zo9-8Rfwhkt68r1r29ty8YwIraXR8eh_1Qwxg7yQXsonBt",
+	})
+	resp := MakeRequest(t, req, http.StatusBadRequest)
+
+	var parsedError auth.AccessTokenErrorResponse
+	require.NoError(t, json.Unmarshal(resp.Body.Bytes(), &parsedError))
+	assert.Equal(t, "unauthorized_client", string(parsedError.ErrorCode))
+	assert.Equal(t, "redirect_uri does not match the authorization request", parsedError.ErrorDescription)
+
+	// Using the correct redirect_uri ("a") should succeed
+	req = NewRequestWithValues(t, "POST", "/login/oauth/access_token", map[string]string{
+		"grant_type":    "authorization_code",
+		"client_id":     "da7da3ba-9a13-4167-856f-3899de0b0138",
+		"client_secret": "4MK8Na6R55smdCY0WuCCumZ6hjRPnGY5saWVRHHjJiA=",
+		"redirect_uri":  "a",
+		"code":          "authcode",
+		"code_verifier": "N1Zo9-8Rfwhkt68r1r29ty8YwIraXR8eh_1Qwxg7yQXsonBt",
+	})
+	MakeRequest(t, req, http.StatusOK)
+}
+
 func TestAccessTokenExchangeWithPublicClient(t *testing.T) {
 	defer tests.PrepareTestEnv(t)()
 	req := NewRequestWithValues(t, "POST", "/login/oauth/access_token", map[string]string{
 		"grant_type":    "authorization_code",
 		"client_id":     "ce5a1322-42a7-11ed-b878-0242ac120002",
-		"redirect_uri":  "http://127.0.0.1",
+		"redirect_uri":  "http://127.0.0.1/",
 		"code":          "authcodepublic",
 		"code_verifier": "N1Zo9-8Rfwhkt68r1r29ty8YwIraXR8eh_1Qwxg7yQXsonBt",
 	})
@@ -497,6 +530,56 @@ func TestRefreshTokenInvalidation(t *testing.T) {
 	assert.Equal(t, "token was already used", parsedError.ErrorDescription)
 }
 
+func TestRefreshTokenCrossClientUsage(t *testing.T) {
+	defer tests.PrepareTestEnv(t)()
+
+	// Step 1: Obtain a refresh token via app 1 (confidential client)
+	req := NewRequestWithValues(t, "POST", "/login/oauth/access_token", map[string]string{
+		"grant_type":    "authorization_code",
+		"client_id":     "da7da3ba-9a13-4167-856f-3899de0b0138",
+		"client_secret": "4MK8Na6R55smdCY0WuCCumZ6hjRPnGY5saWVRHHjJiA=",
+		"redirect_uri":  "a",
+		"code":          "authcode",
+		"code_verifier": "N1Zo9-8Rfwhkt68r1r29ty8YwIraXR8eh_1Qwxg7yQXsonBt",
+	})
+	resp := MakeRequest(t, req, http.StatusOK)
+
+	type tokenResponse struct {
+		AccessToken  string `json:"access_token"`
+		TokenType    string `json:"token_type"`
+		ExpiresIn    int64  `json:"expires_in"`
+		RefreshToken string `json:"refresh_token"`
+	}
+	parsed := new(tokenResponse)
+	require.NoError(t, json.Unmarshal(resp.Body.Bytes(), parsed))
+	assert.NotEmpty(t, parsed.RefreshToken)
+
+	// Step 2: Try to use the refresh token with app 2 (different client): must fail
+	req = NewRequestWithValues(t, "POST", "/login/oauth/access_token", map[string]string{
+		"grant_type":    "refresh_token",
+		"client_id":     "ce5a1322-42a7-11ed-b878-0242ac120002",
+		"client_secret": "4MK8Na6R55smdCY0WuCCumZ6hjRPnGY5saWVRHHjJiA=",
+		"redirect_uri":  "b",
+		"refresh_token": parsed.RefreshToken,
+	})
+	resp = MakeRequest(t, req, http.StatusBadRequest)
+
+	var parsedError auth.AccessTokenErrorResponse
+	require.NoError(t, json.Unmarshal(resp.Body.Bytes(), &parsedError))
+	assert.Equal(t, "invalid_grant", string(parsedError.ErrorCode))
+	assert.Equal(t, "refresh token was not issued to this client", parsedError.ErrorDescription)
+
+	// Step 3: Using the refresh token with the correct app 1 should still work
+	req = NewRequestWithValues(t, "POST", "/login/oauth/access_token", map[string]string{
+		"grant_type":    "refresh_token",
+		"client_id":     "da7da3ba-9a13-4167-856f-3899de0b0138",
+		"client_secret": "4MK8Na6R55smdCY0WuCCumZ6hjRPnGY5saWVRHHjJiA=",
+		"redirect_uri":  "a",
+		"refresh_token": parsed.RefreshToken,
+	})
+	MakeRequest(t, req, http.StatusOK)
+}
+
 func TestSignInOAuthCallbackSignIn(t *testing.T) {
 	defer tests.PrepareTestEnv(t)()
 
diff --git a/tests/integration/wiki_test.go b/tests/integration/wiki_test.go
index 47986177d7..1fd9378852 100644
--- a/tests/integration/wiki_test.go
+++ b/tests/integration/wiki_test.go
@@ -4,19 +4,29 @@
 package integration
 
 import (
+	"encoding/base64"
 	"fmt"
+	"io"
 	"net/http"
 	"net/url"
 	"os"
 	"path/filepath"
 	"strings"
 	"testing"
+	"time"
 
+	auth_model "forgejo.org/models/auth"
+	unit_model "forgejo.org/models/unit"
+	"forgejo.org/models/unittest"
+	user_model "forgejo.org/models/user"
 	"forgejo.org/modules/git"
+	"forgejo.org/modules/optional"
+	api "forgejo.org/modules/structs"
 	"forgejo.org/modules/util"
 	"forgejo.org/tests"
 
 	"github.com/PuerkitoBio/goquery"
+	"github.com/google/uuid"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -24,7 +34,16 @@ import (
 func assertFileExist(t *testing.T, p string) {
 	exist, err := util.IsExist(p)
 	require.NoError(t, err)
-	assert.True(t, exist)
+	if !assert.True(t, exist) {
+		dir := filepath.Dir(p)
+		t.Logf("Listing files that were present in dir path %s", dir)
+		entries, err := os.ReadDir(dir)
+		require.NoError(t, err)
+		for _, e := range entries {
+			t.Logf("file in path %s -> %s", dir, e.Name())
+		}
+		t.Logf("End of %d entries in directory %s", len(entries), dir)
+	}
 }
 
 func assertFileEqual(t *testing.T, p string, content []byte) {
@@ -33,24 +52,162 @@ func assertFileEqual(t *testing.T, p string, content []byte) {
 	assert.Equal(t, content, bs)
 }
 
-func TestRepoCloneWiki(t *testing.T) {
-	onApplicationRun(t, func(t *testing.T, u *url.URL) {
-		dstPath := t.TempDir()
+type (
+	RepoWikiMethod    string
+	RepoWikiAuth      string
+	RepoWikiTarget    string
+	RepoWikiOperation string
+)
 
-		r := fmt.Sprintf("%suser2/repo1.wiki.git", u.String())
-		u, _ = url.Parse(r)
-		u.User = url.UserPassword("user2", userPassword)
-		t.Run("Clone", func(t *testing.T) {
-			require.NoError(t, git.CloneWithArgs(t.Context(), git.AllowLFSFiltersArgs(), u.String(), dstPath, git.CloneRepoOptions{}))
-			assertFileEqual(t, filepath.Join(dstPath, "Home.md"), []byte("# Home page\n\nThis is the home page!\n"))
-			assertFileExist(t, filepath.Join(dstPath, "Page-With-Image.md"))
-			assertFileExist(t, filepath.Join(dstPath, "Page-With-Spaced-Name.md"))
-			assertFileExist(t, filepath.Join(dstPath, "images"))
-			assertFileExist(t, filepath.Join(dstPath, "jpeg.jpg"))
-		})
+const (
+	RepoWikiSSH  RepoWikiMethod = "SSH"
+	RepoWikiHTTP RepoWikiMethod = "HTTP"
+
+	RepoWikiAnonymous                 RepoWikiAuth = "Anonymous"
+	RepoWikiAuthenticated             RepoWikiAuth = "Authenticated"
+	RepoWikiAuthenticatedNonOwnerUser RepoWikiAuth = "Authenticated-NonOwner"
+
+	RepoWikiPublic  RepoWikiTarget = "Public"
+	RepoWikiPrivate RepoWikiTarget = "Private"
+
+	RepoWikiRead  RepoWikiOperation = "Read"
+	RepoWikiWrite RepoWikiOperation = "Write"
+)
+
+func TestRepoWikiGitOperation(t *testing.T) {
+	onApplicationRun(t, func(t *testing.T, u *url.URL) {
+		for _, method := range []RepoWikiMethod{RepoWikiSSH, RepoWikiHTTP} {
+			for _, auth := range []RepoWikiAuth{RepoWikiAnonymous, RepoWikiAuthenticated, RepoWikiAuthenticatedNonOwnerUser} {
+				for _, target := range []RepoWikiTarget{RepoWikiPublic, RepoWikiPrivate} {
+					for _, operation := range []RepoWikiOperation{RepoWikiRead, RepoWikiWrite} {
+						t.Run(fmt.Sprintf("%s/%s/%s/%s", method, auth, target, operation), func(t *testing.T) {
+							defer tests.PrintCurrentTest(t)()
+							doRepoWikiGitOperation(t, u, method, auth, target, operation)
+						})
+					}
+				}
+			}
+		}
 	})
 }
 
+func doRepoWikiGitOperation(t *testing.T, serverURL *url.URL, method RepoWikiMethod, auth RepoWikiAuth, target RepoWikiTarget, operation RepoWikiOperation) {
+	repo := "repo1"
+	if target == RepoWikiPrivate {
+		user2 := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 2})
+		privateRepo, _, reset := tests.CreateDeclarativeRepoWithOptions(t, user2, tests.DeclarativeRepoOptions{
+			IsPrivate:    optional.Some(true),
+			EnabledUnits: optional.Some([]unit_model.Type{unit_model.TypeWiki}),
+		})
+		defer reset()
+
+		session := loginUser(t, user2.LoginName)
+		token := getTokenForLoggedInUser(t, session, auth_model.AccessTokenScopeWriteRepository)
+		urlStr := fmt.Sprintf("/api/v1/repos/%s/%s/wiki/new", user2.LoginName, privateRepo.Name)
+		req := NewRequestWithJSON(t, "POST", urlStr, &api.CreateWikiPageOptions{
+			Title:         "Page With Image",
+			ContentBase64: base64.StdEncoding.EncodeToString([]byte("# Page With Image\n\n![Gitea Logo](./raw/jpeg.jpg)\n")),
+			Message:       "",
+		}).AddTokenAuth(token)
+		MakeRequest(t, req, http.StatusCreated)
+
+		repo = privateRepo.Name
+	}
+
+	dstPath := t.TempDir()
+	r := fmt.Sprintf("%suser2/%s.wiki.git", serverURL.String(), repo)
+	testURL, err := url.Parse(r)
+	require.NoError(t, err)
+
+	if method == RepoWikiHTTP {
+		switch auth {
+		case RepoWikiAnonymous:
+			// no-op
+		case RepoWikiAuthenticated:
+			testURL.User = url.UserPassword("user2", userPassword)
+		case RepoWikiAuthenticatedNonOwnerUser:
+			testURL.User = url.UserPassword("user20", userPassword)
+		default:
+			t.Fatalf("unexpected auth = %s", auth)
+		}
+
+		doRepoWikiGitOperationInner(t, testURL, dstPath, auth, target, operation)
+	} else if method == RepoWikiSSH {
+		var user string
+		switch auth {
+		case RepoWikiAnonymous:
+			t.Skip() // anonymous ssh is not supported
+		case RepoWikiAuthenticated:
+			user = "user2" // owner of the repo
+		case RepoWikiAuthenticatedNonOwnerUser:
+			user = "user20" // not the owner of the repo, not a collaborator
+		default:
+			t.Fatalf("unexpected auth = %s", auth)
+		}
+
+		keyname := "my-testing-key"
+		withKeyFile(t, keyname, func(keyFile string) {
+			baseAPITestContext := NewAPITestContext(t, user, repo, auth_model.AccessTokenScopeWriteUser)
+			t.Run("CreateUserKey", doAPICreateUserKey(baseAPITestContext, fmt.Sprintf("test-key-%s", uuid.New().String()), keyFile, func(t *testing.T, pk api.PublicKey) {}))
+
+			baseAPITestContext.Username = "user2" // target repo owner to compose URLs
+			baseAPITestContext.Reponame = fmt.Sprintf("%s.wiki", repo)
+			testURL = createSSHUrl(baseAPITestContext.GitPath(), testURL)
+
+			doRepoWikiGitOperationInner(t, testURL, dstPath, auth, target, operation)
+		})
+	} else {
+		t.Fatalf("unexpected method = %s", method)
+	}
+}
+
+func doRepoWikiGitOperationInner(t *testing.T, gitURL *url.URL, dstPath string, auth RepoWikiAuth, target RepoWikiTarget, operation RepoWikiOperation) {
+	err := git.CloneWithArgs(t.Context(), git.AllowLFSFiltersArgs(), gitURL.String(), dstPath, git.CloneRepoOptions{})
+	if target == RepoWikiPrivate && (auth == RepoWikiAnonymous || auth == RepoWikiAuthenticatedNonOwnerUser) {
+		require.Error(t, err, "clone must fail; auth %s shouldn't be able to access private repo")
+		return // no other test conditions to satisfy if the clone failed
+	}
+	require.NoError(t, err, "clone must succeed; auth %s should be able to access a public repo")
+
+	assertFileExist(t, filepath.Join(dstPath, "Page-With-Image.md"))
+	assertFileEqual(t, filepath.Join(dstPath, "Page-With-Image.md"), []byte("# Page With Image\n\n![Gitea Logo](./raw/jpeg.jpg)\n"))
+
+	if operation == RepoWikiWrite {
+		f, err := os.OpenFile(filepath.Join(dstPath, "Home.md"), os.O_WRONLY|os.O_TRUNC|os.O_CREATE, 0o644)
+		defer f.Close()
+		require.NoError(t, err)
+		_, err = io.WriteString(f, fmt.Sprintf("# Home Page Edited!\n%s", uuid.New().String()))
+		require.NoError(t, err)
+		err = f.Close()
+		require.NoError(t, err)
+
+		err = git.AddChanges(dstPath, true)
+		require.NoError(t, err)
+		err = git.CommitChanges(dstPath, git.CommitChangesOptions{Message: "Changes made!"})
+		require.NoError(t, err)
+
+		// don't use git.Push() because it doesn't support credential helper, and 'origin' would have had its URL saved
+		// with the creds stripped in dstPath so we need the credential helper to be configured.
+		cmd := git.NewCommand(t.Context())
+		if gitURL.Scheme == "http" {
+			_, credCleanup, err := cmd.AddAuthCredentialHelperForRemote(gitURL.String())
+			require.NoError(t, err)
+			defer credCleanup()
+		}
+		cmd.AddArguments("push", "origin")
+
+		stdout, stderr, err := cmd.RunStdString(&git.RunOpts{
+			Dir:     dstPath,
+			Timeout: 2 * time.Second,
+		})
+		if auth == RepoWikiAuthenticated {
+			require.NoError(t, err, "stdout = %q, stderr = %q", stdout, stderr)
+		} else {
+			require.Error(t, err, "push must fail as authentication mode %s doesn't allow write, but succeeded.  stdout = %q, stderr = %q", auth, stdout, stderr)
+		}
+	}
+}
+
 func Test_RepoWikiPages(t *testing.T) {
 	defer tests.PrepareTestEnv(t)()