Low [CVE-2026-18569] OIDC backchannel logout accepts unsigned forged logout tokens
This low-severity Red Hat Linux advisory covers CVE-2026-18569 affecting Red Hat Build of Keycloak.
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Summary
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. Weakness: CWE-347.
Affected Red Hat products: Red Hat Build of Keycloak. Red Hat lists Red Hat Data Grid 8; Red Hat JBoss Enterprise Application Platform Expansion Pack; Red Hat Single Sign-On 7 as not affected.
Red Hat does not currently list a fixing RHSA for this CVE.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · high-confidence parse· fetched 28 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 28 days ago·verify at source
Mitigation checklist
- 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.
Official advisory · high-confidence parse· fetched 28 days ago·verify at source
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