CVE-2025-2559: Keycloak services Denial of Service Vulnerability

MODERATE
Advisory Identifier: GHSA-2935-2wfm-hhpv
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CVSS 4.9
CWE-770
Published
Advisory Summary

CVE-2025-2559 is a MODERATE (CVSS 4.9) denial of service vulnerability (CWE-770: Allocation of Resources Without Limits or Throttling) affecting Keycloak services libraries in the Maven ecosystem. The issue involves keycloak denial of service (dos) vulnerability via jwt token cache. Remediation is available in the latest vendor maintenance releases.

CVE-2025-2559 at a Glance

CVE Identifier CVE-2025-2559
GHSA Identifier GHSA-2935-2wfm-hhpv
Severity MODERATE
CVSS v3.1 Base Score 4.9
CWE Classification CWE-770: Allocation of Resources Without Limits or Throttling
Affected Product Keycloak services
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 4.9

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required High (PR:H)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity None (I:N)
Availability High (A:H)

How to Fix CVE-2025-2559

To remediate this vulnerability, upgrade all affected Keycloak services dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

org.keycloak:keycloak-services fixed: Latest secure release 
<dependency>
    <groupId>org.keycloak</groupId>
    <artifactId>keycloak-services</artifactId>
    <version>Latest secure release</version>
</dependency>
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

mvn dependency:tree -Dincludes=org.keycloak

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2025-2559, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree -Dincludes=org.keycloak

Analyze the terminal output to locate any version of Keycloak services in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than the patched release), your application is affected.

Note: The mvn dependency:tree -Dincludes=org.keycloak command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-770: Allocation of Resources Without Limits or Throttling, where the product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated. In Keycloak services, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

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.

CVE-2025-2559 Affected Keycloak services Versions

1 component(s)
Product / Package Ecosystem Affected Versions Fixed Version
org.keycloak:keycloak-services
maven/org.keycloak/keycloak-services
Maven
≤ 26.1.4

References

NVD — CVE-2025-2559 NVD
https://nvd.nist.gov/vuln/detail/CVE-2025-2559
access.redhat.com/errata/rhsa-2025:43... WEB
https://access.redhat.com/errata/RHSA-2025:4335
access.redhat.com/errata/rhsa-2025:43... WEB
https://access.redhat.com/errata/RHSA-2025:4336
Keycloak services Security Information SECURITY
https://access.redhat.com/security/cve/CVE-2025-2559
bugzilla.redhat.com/show_bug.cgi WEB
https://bugzilla.redhat.com/show_bug.cgi?id=2353868
Keycloak services Source Repository REPOSITORY
https://github.com/keycloak/keycloak

Frequently Asked Questions

What is CVE-2025-2559?
CVE-2025-2559 is a security vulnerability in Keycloak services involving Keycloak Denial of Service (DoS) Vulnerability via JWT Token Cache under CWE-770: Allocation of Resources Without Limits or Throttling.
Which Keycloak services versions are affected?
Affected versions include releases prior to current release patches across affected packages: org.keycloak:keycloak-services.
What version fixes CVE-2025-2559?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
Is keycloak-services affected?
Yes, org.keycloak:keycloak-services is affected in releases prior to Latest secure release. Upgrade your dependency to Latest secure release or later.
What is the CVSS score of CVE-2025-2559?
CVE-2025-2559 has a CVSS v3.1 base score of 4.9 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2025-2559?
CVE-2025-2559 is classified under CWE-770: Allocation of Resources Without Limits or Throttling (The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.).
How can I check Maven dependencies for CVE-2025-2559?
Run the dependency tree command: 'mvn dependency:tree -Dincludes=org.keycloak'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-2935-2wfm-hhpv",
  "modified" : "2025-04-30T03:30:31Z",
  "published" : "2025-03-25T09:32:07Z",
  "aliases" : [ "CVE-2025-2559" ],
  "summary" : "Keycloak Denial of Service (DoS) Vulnerability via JWT Token Cache",
  "details" : "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.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.keycloak:keycloak-services"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "26.1.4"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2025-2559"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/errata/RHSA-2025:4335"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/errata/RHSA-2025:4336"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/security/cve/CVE-2025-2559"
  }, {
    "type" : "WEB",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=2353868"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/keycloak/keycloak"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-770" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2025-03-25T16:50:25Z",
    "nvd_published_at" : "2025-03-25T09:15:17Z"
  }
}