Keycloak provides a feature called mTLS holder-of-key binding which ensures that a token can only be used by the client that originally requested it by binding it to their digital certificate. A flaw was discovered where the new Standard Token Exchange V2 feature does not check for this certificate. This allows an attacker with stolen client credentials to obtain a standard, unrestricted token that bypasses these security protections.
Last checked: 2026-09-25 16:08 UTC
No exploitation evidence · CISA Coordinator (Assessed 2026-09-25 13:52 UTC)
Fix evidence last checked: 2026-09-25 07:05 UTC