Reliance on Untrusted Inputs in a Security Decision in Keycloak - CVE-2026-16093
Published: July 17, 2026 / Updated: September 5, 2026
Vulnerability identifier: #VU146965
CSH Severity: Low
CVSS v4: 5.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-16093
CWE-ID: CWE-807
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to bypass client authentication policy requirements.
The vulnerability exists due to reliance on untrusted inputs in a security decision in the Client Policies enforcement mechanism when processing client assertion headers. A remote user can provide a fake unsigned assertion header to bypass the policy requirements.
Exploitation requires valid client credentials.
Affected software
Keycloak
How to mitigate CVE-2026-16093
Install security update from vendor's website.
Keycloak - update to 26.7.3