Keycloak CIBA flow bypass for account lock via brute-force
CVE-2026-9798 Published on May 28, 2026
Keycloak: keycloak: brute-force protection bypass in ciba flow
A flaw was found in Keycloak, an open-source identity and access management solution. When a user account is temporarily locked due to repeated failed login attempts, an attacker with valid client credentials can exploit the Client-Initiated Backchannel Authentication (CIBA) flow to bypass this brute-force protection. This allows continued authentication attempts and token issuance even when the account should be locked, potentially enabling further unauthorized access attempts.
Vulnerability Analysis
CVE-2026-9798 is exploitable with network access, requires user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality, a small impact on integrity and availability.
Timeline
Reported to Red Hat.
Made public.
Weakness Type
Authentication Bypass by Primary Weakness
The authentication algorithm is sound, but the implemented mechanism can be bypassed as the result of a separate weakness that is primary to the authentication error.
Products Associated with CVE-2026-9798
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