CVE-2026-94218 in Keycloak
Summary
by MITRE • 09/21/2026
A flaw was found in the authentication session management of Keycloak, an identity and access management solution. The issue occurs when an administrator enforces a stronger authentication flow, such as mandatory two-factor authentication (2FA) setup, through a client policy. A user can bypass this requirement by manually visiting a specific session restart web link during the login process. This action clears the internal markers that track the required security steps, allowing the user to log in with only a password and gain access without completing the mandated 2FA setup.
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Analysis
by VulDB Data Team • 09/21/2026
The vulnerability identified in Keycloak represents a critical failure in authentication session management, specifically within the logic governing enforced multi-factor authentication policies. As an identity and access management solution, Keycloak is responsible for verifying user identities and enforcing security policies defined by administrators. In this scenario, the flaw manifests when an administrator configures a client policy to mandate stronger authentication flows, such as requiring users to set up two-factor authentication before gaining full system access. The core technical defect lies in how the application handles session state transitions during the login process. When a user is directed to complete mandatory security steps like 2FA setup, Keycloak relies on internal markers or flags within the active session object to track progress through these required stages. However, the implementation fails to properly validate that these prerequisites have been met when specific navigation actions are taken by the client side.
The operational impact of this flaw is severe because it allows for a complete bypass of mandatory security controls without requiring any exploitation of complex logic or external tools. An attacker or malicious insider can simply visit a specific session restart web link during the login sequence. This action triggers a reset of the authentication context, effectively clearing the internal markers that indicate which security steps have been completed and which remain pending. Consequently, when the user proceeds to log in after this manual intervention, the system treats the session as if it is starting fresh from an initial state where only basic password verification is required. The application fails to re-evaluate or enforce the previously mandated two-factor authentication requirement because the flag indicating that 2FA setup was pending has been erroneously cleared by the session restart action. This results in unauthorized access being granted based solely on knowledge of a static credential, thereby nullifying the intended security posture established by the administrator.
From a classification perspective, this vulnerability aligns with CWE-384, Session Fixation, although it is more accurately described as a failure to maintain authentication state integrity during session manipulation. It also relates closely to CWE-287, Improper Authentication, because the system fails to correctly verify that all required authentication factors have been presented before granting access. In terms of offensive security frameworks such as MITRE ATT&CK, this behavior facilitates lateral movement and initial access by allowing an adversary who has obtained a valid password to bypass additional layers of defense designed to protect high-value accounts or sensitive data stores. The ability to reset the session state effectively strips away the multi-factor layer that is supposed to provide defense-in-depth against credential theft.
Mitigation strategies must focus on ensuring that authentication policies are enforced consistently regardless of how the user navigates through the login flow. Developers should implement server-side validation checks at every step of the authentication process, rather than relying solely on client-side state or session markers that can be manipulated by simple URL visits. It is essential to verify the completeness of all required authentication factors before issuing any access tokens or granting entry to protected resources. Additionally, implementing strict session management practices where sensitive policy requirements are bound tightly to the specific execution context and cannot be reset without re-authenticating against those policies would prevent this bypass. Administrators should also monitor for unusual login patterns that might indicate attempts to exploit this state manipulation technique until a patch is applied by the Keycloak maintainers.