CVE-2026-34179: LXD: Update of type field in restricted TLS certificate allows privilege escalation to cluster admin

April 10, 2026

A restricted TLS certificate user can escalate to cluster admin by changing their certificate type from client to server via PUT/PATCH to /1.0/certificates/{fingerprint}. The non-admin guard and reset block in doCertificateUpdate fail to validate or reset the Type field, allowing a caller-supplied value to persist to the database. The modified certificate is matched as a server certificate during TLS authentication, granting ProtocolCluster with full admin privileges.

References

github.com/advisories/GHSA-c3h3-89qf-jqm5
github.com/canonical/lxd
github.com/canonical/lxd/pull/17936
github.com/canonical/lxd/security/advisories/GHSA-c3h3-89qf-jqm5
nvd.nist.gov/vuln/detail/CVE-2026-34179

Code Behaviors & Features

Detect and mitigate CVE-2026-34179 with GitLab Dependency Scanning

Secure your software supply chain by verifying that all open source dependencies used in your projects contain no disclosed vulnerabilities. Learn more about Dependency Scanning →