CVE-2026-109553
CVE-2026-109553 · Gitea SSH certificate principal impersonation of other users
This page contains facts from public vulnerability sources. Check the original advisory before updating.
Gitea resolved the principals of an SSH certificate by searching the content of all stored public keys instead of only principal keys. When Gitea trusts a user certificate authority (`SSH_TRUSTED_USER_CA_KEYS`) and accepts arbitrary principals (`SSH_AUTHORIZED_PRINCIPALS_ALLOW=anything`), a user could register another user's public key line as their own principal, or a holder of a certificate signed by that authority could list it, and then authenticate as the owner of that key through the HTTP signature API and the built-in SSH server. Instances that do not trust a user certificate authority are not affected.
CVSS 7.5 · High · EPSS 0.2%
- Published
- Updated
Affected products and versions
gitea
- Versions
- ≥ 0, ≤ 28.1.0: Affected (semver)
No fix published
Original sources
- https://github.com/go-gitea/gitea/security/advisories/GHSA-vcp6-2qc6-gvq3
- https://github.com/go-gitea/gitea/pull/39839
- https://github.com/go-gitea/gitea/pull/39847
- https://blog.gitea.com/release-of-28.2.0/
- https://github.com/go-gitea/gitea/releases/tag/v28.2.0
- https://nvd.nist.gov/vuln/detail/CVE-2026-109553