2026-05-12 security patches (#12493)

- 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

<!--start release-notes-assistant-->

## Release notes
<!--URL:https://codeberg.org/forgejo/forgejo-->
- Security bug fixes
  - [PR](https://codeberg.org/forgejo/forgejo/pulls/12493): <!--number 12493 --><!--line 0 --><!--description MjAyNi0wNS0xMiBzZWN1cml0eSBwYXRjaGVz-->2026-05-12 security patches<!--description-->
<!--end release-notes-assistant-->

Co-authored-by: Derzsi Dániel <daniel@tohka.us>
Co-authored-by: jvoisin <julien.voisin@dustri.org>
Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/12493

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 {

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