Bug 2435257 (CVE-2026-1609)

Summary: CVE-2026-1609 org.keycloak/keycloak-quarkus-server: Keycloak: Unauthorized Access via JWT authorization grant with disabled users
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: asoldano, bbaranow, bmaxwell, brian.stansberry, darran.lofthouse, dosoudil, fjuma, istudens, ivassile, iweiss, mosmerov, msvehla, nwallace, pberan, pesilva, pjindal, pmackay, rstancel, security-response-team, smaestri, tom.jenkinson
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Keycloak. When the JSON Web Token (JWT) authorization grant preview feature is enabled and a user account is disabled, Keycloak fails to validate the user’s disabled status during JWT authorization grant processing. A remote attacker with low privileges can exploit this improper access control vulnerability by presenting a valid assertion token from an external identity provider to obtain a JWT for a disabled user. This allows unauthorized access to sensitive resources.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-01-29 12:17:38 UTC 
Improper access control vulnerability in the JWT authorization grant preview feature of Keycloak. The issue occurs when the --features jwt-authorization-grant option is enabled, and a user account is disabled. Keycloak fails to validate the user’s disabled status during JWT authorization grant processing. By presenting a valid assertion token from an external identity provider, an attacker can obtain a JWT for a disabled user and use it to access protected endpoints. This can be exploited remotely with low privileges and no user interaction, resulting in unauthorized access to sensitive resources.