CVE-2026-1609
Description
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.
Statement
The Red Hat Product Security team has assessed this vulnerability as High severity; however, it only affects upstream Keycloak version 26.5.2, which includes a preview JWT authorization grant feature. No released Red Hat Build of Keycloak (RHBK) versions are impacted, as this feature has not been shipped in any downstream product. The issue arises from improper enforcement of user disabled-state checks during JWT authorization grant processing, potentially allowing unauthorized access when the preview feature is explicitly enabled. Red Hat products remain unaffected at this time.
Mitigation
To mitigate this issue, ensure that the `jwt-authorization-grant` preview feature is not enabled in Keycloak deployments. This feature is typically disabled by default. If it has been explicitly enabled, it should be disabled to prevent unauthorized access by disabled user accounts. Consult Keycloak documentation for specific instructions on managing preview features and configuration. A restart of the Keycloak service may be required after disabling the feature for the changes to take effect.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 8.1 | N/A | 8.1 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | Low |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | High | N/A | High |
| Integrity Impact | High | N/A | High |
| Availability Impact | None | N/A | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
cve.org: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Understanding the Weakness (CWE)
Other
Technical Impact: Varies by Context
Acknowledgements
Red Hat would like to thank Joy Gilbert and Reynaldo Immanuel for reporting this issue.
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