CVE-2026-1190 identifies a security flaw in the Red Hat Build of Keycloak, specifically within its Security Assertion Markup Language (SAML) brokering functionality. Keycloak acts as a client in SAML federated authentication setups, where it processes SAML responses containing assertions about user identity and session validity. The vulnerability arises because Keycloak does not properly validate the NotOnOrAfter timestamp within the SubjectConfirmationData element of a SAML response. This timestamp is intended to specify the expiration time of the assertion, ensuring that authentication tokens are only valid for a limited window. By failing to enforce this validation, an attacker can manipulate or delay the expiration timestamp, effectively extending the period during which a SAML response is accepted as valid. This can lead to sessions remaining active beyond their intended lifespan, potentially allowing unauthorized prolonged access or causing resource exhaustion due to extended session durations. The CVSS score of 3.1 reflects a low severity, influenced by the need for user interaction, high attack complexity, and the absence of direct confidentiality or availability impacts. No known exploits have been reported in the wild, and no patches are currently linked, indicating that the vulnerability is newly disclosed and not yet widely exploited. However, the flaw highlights a critical aspect of SAML security—proper validation of assertion timestamps is essential to prevent session hijacking or replay attacks. Organizations using Keycloak in SAML configurations should be aware of this issue and prepare to apply fixes or mitigations.

For European organizations, the impact of CVE-2026-1190 is primarily related to authentication session management and potential security policy violations. Extended session durations caused by manipulated NotOnOrAfter timestamps could allow attackers to maintain access to protected resources longer than intended, increasing the risk of unauthorized access if credentials or tokens are compromised. While the vulnerability does not directly compromise confidentiality or availability, it can undermine trust in the authentication system and complicate incident response. Additionally, prolonged sessions may lead to increased resource consumption on identity providers or service providers, potentially affecting performance. Organizations in sectors with strict compliance requirements around session timeouts and access controls—such as finance, healthcare, and government—may face regulatory risks if this vulnerability is exploited. The low severity rating suggests that exploitation is not straightforward, but the potential for subtle security policy bypasses warrants attention, especially in environments relying heavily on SAML for single sign-on (SSO) and federated identity management.

To mitigate CVE-2026-1190, organizations should: 1) Monitor Red Hat and Keycloak vendor advisories closely and apply patches or updates as soon as they become available to address the timestamp validation flaw. 2) Implement strict session management policies that enforce maximum session durations independent of SAML assertion timestamps, such as server-side session timeouts and periodic re-authentication requirements. 3) Enhance logging and monitoring of SAML authentication events to detect anomalies in session durations or repeated use of stale assertions. 4) Consider deploying additional validation layers or custom extensions in Keycloak to enforce NotOnOrAfter timestamp checks if patching is delayed. 5) Educate security teams and application developers about the importance of validating SAML assertion timestamps and the risks of extended session validity. 6) Review and tighten SAML configuration settings, including clock synchronization between identity providers and service providers, to minimize timing-related issues. 7) Conduct regular security assessments and penetration testing focused on SAML authentication flows to identify potential weaknesses.