CVE-2025-2559: Allocation of Resources Without Limits or Throttling
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.
AI Analysis
Technical Summary
The vulnerability CVE-2025-2559 in Red Hat build of Keycloak arises from caching JWT tokens until their expiration without limits or throttling. When JWT tokens have very long expiration times (e.g., 24 or 48 hours), the cache can grow indefinitely, exhausting memory resources and causing an OutOfMemoryError. This results in a denial of service (DoS) condition that disrupts legitimate user access. The issue affects Keycloak versions from 23.0.0 to 26.1.0. Red Hat has issued security advisories RHSA-2025:4335 and RHSA-2025:4336, releasing updated Keycloak 26.0.11 images that fix this vulnerability. The advisories recommend backing up existing installations before applying the update.
Potential Impact
The vulnerability can cause an OutOfMemoryError due to unbounded growth of the JWT token cache when tokens have excessively long expiration times. This leads to a denial of service condition, preventing legitimate users from accessing the Keycloak authentication system. There is no impact on confidentiality or integrity reported. The CVSS v3.1 base score is 4.9 (medium severity), reflecting network attack vector, low attack complexity, high privileges required, no user interaction, and impact limited to availability.
Mitigation Recommendations
Red Hat has released fixed versions of the Red Hat build of Keycloak (version 26.0.11) that address this vulnerability. Users should back up their existing installations, including applications, configuration files, and databases, before applying the update. Applying the updated Keycloak images as provided in Red Hat advisories RHSA-2025:4335 and RHSA-2025:4336 will mitigate the risk of denial of service caused by JWT token cache exhaustion. Patch status is confirmed as fixed by Red Hat. No additional mitigation steps are specified by the vendor.
CVE-2025-2559: Allocation of Resources Without Limits or Throttling
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.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability CVE-2025-2559 in Red Hat build of Keycloak arises from caching JWT tokens until their expiration without limits or throttling. When JWT tokens have very long expiration times (e.g., 24 or 48 hours), the cache can grow indefinitely, exhausting memory resources and causing an OutOfMemoryError. This results in a denial of service (DoS) condition that disrupts legitimate user access. The issue affects Keycloak versions from 23.0.0 to 26.1.0. Red Hat has issued security advisories RHSA-2025:4335 and RHSA-2025:4336, releasing updated Keycloak 26.0.11 images that fix this vulnerability. The advisories recommend backing up existing installations before applying the update.
Potential Impact
The vulnerability can cause an OutOfMemoryError due to unbounded growth of the JWT token cache when tokens have excessively long expiration times. This leads to a denial of service condition, preventing legitimate users from accessing the Keycloak authentication system. There is no impact on confidentiality or integrity reported. The CVSS v3.1 base score is 4.9 (medium severity), reflecting network attack vector, low attack complexity, high privileges required, no user interaction, and impact limited to availability.
Mitigation Recommendations
Red Hat has released fixed versions of the Red Hat build of Keycloak (version 26.0.11) that address this vulnerability. Users should back up their existing installations, including applications, configuration files, and databases, before applying the update. Applying the updated Keycloak images as provided in Red Hat advisories RHSA-2025:4335 and RHSA-2025:4336 will mitigate the risk of denial of service caused by JWT token cache exhaustion. Patch status is confirmed as fixed by Red Hat. No additional mitigation steps are specified by the vendor.
Technical Details
- Data Version
- 5.1
- Assigner Short Name
- redhat
- Date Reserved
- 2025-03-20T12:22:59.504Z
- Cisa Enriched
- true
- Cvss Version
- 3.1
- State
- PUBLISHED
- Vendor Advisory Urls
- [{"url":"https://access.redhat.com/errata/RHSA-2025:4335","vendor":"Red Hat"},{"url":"https://access.redhat.com/errata/RHSA-2025:4336","vendor":"Red Hat"},{"url":"https://access.redhat.com/security/cve/CVE-2025-2559","vendor":"Red Hat"}]
Threat ID: 682d983bc4522896dcbee413
Added to database: 5/21/2025, 9:09:15 AM
Last enriched: 5/7/2026, 1:45:18 AM
Last updated: 5/8/2026, 5:52:54 PM
Views: 101
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