CVE Catalog

CVE-2026-109553

HighCVSS 7.5
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.20%

10th percentile - higher than 10% of all known CVEs

Summary

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.

Risk Assessment

Impersonation of another user and gaining their privileges, potentially leading to unauthorized access to repositories and data. Only affects instances with user certificate authority trust and arbitrary principals enabled.

Recommendation

Update Gitea to a version containing the fix. If possible, disable SSH_TRUSTED_USER_CA_KEYS or restrict SSH_AUTHORIZED_PRINCIPALS_ALLOW to safe values.

Other vulnerabilities in Gitea

See all
Original NVD description (English source)

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.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS