GHSA-j2w3-9c3r-g83q: Gitea: Private Repository Metadata Remains Accessible After Access Revocation

Summary A user who previously had access to a private repository can continue to obtain repository metadata through GET /api/v1/user/starred after their access to the repository has been revoked. After a collaborator is removed from a private repository, direct access to the repository is correctly denied. However, the repository may still appear in the user's starred repository list, and the endpoint continues to return repository metadata. Changes made to that metadata after access revocation are also reflected in subsequent responses. Details The issue affects the authenticated endpoint: GET /api/v1/user/starred The same behavior was also observed on: GET /api/v1/user/subscriptions A reproducible scenario is: 1. User alice creates a private repository. 2. User bob is granted collaborator access. 3. bob stars the repository. 4. alice removes bob from the repository collaborators. 5. Direct repository access by bob is denied. 6. bob requests /api/v1/user/starred. 7. The repository is still present in the response together with repository metadata. Additionally, if repository metadata is modified after access revocation, the updated values are returned by /api/v1/user/starred. As a result, a user who no longer has permission to access the repository can continue to obtain repository metadata through the starred repository list. PoC PoC Link https://anonymous.4open.science/r/Gitea_PoC-EC93/5_poc_starred_list PoC Details 1. Create a private repository: alice/P description = "INITIAL" 2. Add bob as a collaborator with read access. 3. As bob, star the repository: PUT /api/v1/user/starred/alice/P Response: 204 No Content 4. Remove bob from the collaborator list. 5. Update the repository description: description = "AFTER-REVOKE" 6. Verify that direct repository access is no longer allowed: GET /api/v1/repos/alice/P Response: 404 Not Found 7. As bob, request the starred repository list: GET /api/v1/user/starred The response still contains the