SSH Certificate Principal Vulnerability in Gitea by Gitea
CVE-2026-109553

7.5HIGH

Key Information:

Vendor

Gitea

Status
Gitea
Vendor
CVE Published:
18 October 2026

What is CVE-2026-109553?

A security flaw in Gitea's handling of SSH certificates allows attackers to impersonate other users by exploiting the incorrect resolution of principals from public keys. When user certificate authority settings are trusted, it enables potential unauthorized access to accounts by registering other user’s public keys as one’s own. Instances not trusting a user certificate authority remain unaffected, emphasizing the need for careful configuration to mitigate this vulnerability.

Affected Version(s)

Gitea 0 <= 28.1.0

References

https://github.com/go-gitea/gitea/security/advisories/GHS...
vendor-advisory
https://github.com/go-gitea/gitea/pull/39839
patch
https://github.com/go-gitea/gitea/pull/39847
patch

CVSS V3.1

Score:
7.5
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
High
Privileges Required:
Low
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

https://github.com/DshtAnger
https://github.com/silverwind
https://github.com/wxiaoguang
https://github.com/bircni
.