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 ...

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.

Metrics

CVSS 3.1

4.9/10

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

EPSS Probability

0.65%

46.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-770

References

Timeline

Published: Mar 25, 2025
Last Modified: Jun 17, 2026
Status: Deferred

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.

How severe is CVE-2025-2559?

CVE-2025-2559 has a CVSS score of 4.9/10 (MEDIUM severity). The EPSS model estimates a 0.65% probability of exploitation in the next 30 days.

How do I fix CVE-2025-2559?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.