CVE-2026-1609: Access Control Flaw (CVSS 8.1)

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.

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CVSS v3.1 Score

8.1

HIGH

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

EPSS — Exploit Prediction

0.0051

Probability of exploitation

0.40%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-284 CWE-284

References

Other References

https://access.redhat.com/security/cve/CVE-2026-1609 https://bugzilla.redhat.com/show_bug.cgi?id=2435257 https://github.com/keycloak/keycloak/issues/46144 https://github.com/keycloak/keycloak/releases/tag/26.5.3 https://access.redhat.com/security/cve/CVE-2026-1609 https://bugzilla.redhat.com/show_bug.cgi?id=2435257 https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-1609.json

Frequently Asked Questions

What is CVE-2026-1609? +

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. It has a CVSS v3.1 base score of 8.1 (HIGH).

How severe is CVE-2026-1609? +

CVE-2026-1609 has a CVSS v3.1 score of 8.1 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0051, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-1609? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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