CVE-2025-2559: DoS (CVSS 4.9)

Description

A flaw was found in Keycloak. When the configuration uses JWT tokens for authentication, the tokens are cached until expiration. If a client uses JWT tokens with an excessively long expiration time, for example, 24 or 48 hours, the cache can grow indefinitely, leading to an OutOfMemoryError. This issue could result in a denial of service condition, preventing legitimate users from accessing the system.

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CVSS v3.1 Score

4.9

MEDIUM

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

Weakness Type (CWE)

CWE-770 CWE-770

References

Other References

https://access.redhat.com/errata/RHSA-2025:4335 https://access.redhat.com/errata/RHSA-2025:4336 https://access.redhat.com/security/cve/CVE-2025-2559 https://bugzilla.redhat.com/show_bug.cgi?id=2353868 https://github.com/keycloak/keycloak/commit/a10c8119d4452b866b90a9019b2cc159919276ca https://github.com/keycloak/keycloak/issues/38576

Frequently Asked Questions

What is CVE-2025-2559? +

A flaw was found in Keycloak. When the configuration uses JWT tokens for authentication, the tokens are cached until expiration. If a client uses JWT tokens with an excessively long expiration time, for example, 24 or 48 hours, the cache can grow indefinitely, leading to an OutOfMemoryError. This issue could result in a denial of service condition, preventing legitimate users from accessing the system. It has a CVSS v3.1 base score of 4.9 (MEDIUM).

How severe is CVE-2025-2559? +

CVE-2025-2559 has a CVSS v3.1 score of 4.9 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

How do I check if I'm vulnerable to CVE-2025-2559? +

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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