Gitea's shared comparison helper omits the token repository-access check used when updating pull…

Why it is Yellow

• CVSS 6.5 medium

References

• https://blog.gitea.com/release-of-1.27.3/
• https://github.com/go-gitea/gitea/pull/39006
• https://github.com/go-gitea/gitea/pull/39013
• https://github.com/go-gitea/gitea/releases/tag/v1.27.3
• https://github.com/go-gitea/gitea/security/advisories/GHSA-m78w-jjjx-gp8r

Original description

Gitea's shared comparison helper omits the token repository-access check used when updating pull requests. A public-only token with read:repository scope can route a comparison or pull request creation through a public base repository and retrieve commit history and diffs from a private head repository accessible to the token owner. This bypasses the token's public-only restriction; it does not remove the account's underlying repository permission checks.