Gitea accepted pushed Git trees containing two entries with the same name, which Git's own…

Why it is Amber

• CVSS 9.1 critical
• Remotely exploitable without logging in

References

• https://blog.gitea.com/release-of-28.0.0/
• https://github.com/go-gitea/gitea/pull/39472
• https://github.com/go-gitea/gitea/releases/tag/v28.0.0
• https://github.com/go-gitea/gitea/security/advisories/GHSA-6pv5-8rp7-8c75

Original description

Gitea accepted pushed Git trees containing two entries with the same name, which Git's own consistency checks reject. Gitea's web views resolved such a path to the first entry, while `git checkout`, Gitea Actions, and release archives use the last. A contributor could open a pull request whose diff and file views show benign content while CI and checkouts at the same commit use different, attacker-controlled content. Incoming objects are now checked for consistency; objects already stored in existing repositories are not rescanned.