GHSA-C3H3-89QF-JQM5 LXD: Update of type field in restricted TLS certificate allows privilege escalation to cluster admin

Summary 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...