Copyright © 2012 Red Hat, Inc. All rights reserved. Low 2026-07-31T10:18:53 keycloak-services: keycloak-services: OIDC backchannel logout accepts unsigned forged logout tokens 3.7 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L CWE-347

A flaw was found in the backchannel logout endpoint of the keycloak-services component, which is part of the Red Hat Build of Keycloak. This component handles authentication and session management for applications. The issue occurs when an OIDC identity provider is configured to skip signature validation. In this specific setup, the system incorrectly accepts logout requests that have no cryptographic signature. An attacker who knows certain technical details about a user's session can use this flaw to force that user to be logged out, potentially disrupting their work.

A flaw was found in the backchannel logout endpoint of the keycloak-services component, which is part of the Red Hat Build of Keycloak. This component handles authentication and session management for applications. The issue occurs when an OIDC identity provider is configured to skip signature validation. In this specific setup, the system incorrectly accepts logout requests that have no cryptographic signature. An attacker who knows certain technical details about a user's session can use this flaw to force that user to be logged out, potentially disrupting their work.

The Red Hat Product Security team has assessed the severity of this vulnerability as Low, given that it requires a non-default insecure configuration and knowledge of specific session identifiers to exploit. Successful exploitation allows an attacker to force-logout targeted brokered users, leading to a limited denial of service for those individuals. The vulnerability's root cause is the failure to enforce signature validation on backchannel logout tokens when the identity provider's signature validation setting is disabled. Red Hat would like to thank Paul Bottinelli (Trail of Bits) for reporting this issue. Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability. Red Hat Build of Keycloak Affected keycloak-services Red Hat Build of Keycloak Affected rhbk-keycloak-rhel9/rhbk-keycloak-rhel9 Red Hat Build of Keycloak Affected rhbk-openshift-rhel9/rhbk-openshift-rhel9 Red Hat Data Grid 8 Not affected keycloak-services Red Hat JBoss Enterprise Application Platform Expansion Pack Not affected keycloak-services Red Hat Single Sign-On 7 Not affected keycloak-services https://www.cve.org/CVERecord?id=CVE-2026-18569 https://nvd.nist.gov/vuln/detail/CVE-2026-18569