CVE-2025-11419
Unknown Unknown - Not Provided
TLS Renegotiation DoS Vulnerability in Keycloak Server

Publication date: 2025-12-23

Last updated on: 2026-04-20

Assigner: Red Hat, Inc.

Description
A flaw was found in Keycloak. This vulnerability allows an unauthenticated remote attacker to cause a denial of service (DoS) by repeatedly initiating TLS 1.2 client-initiated renegotiation requests to exhaust server CPU resources, making the service unavailable.
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Meta Information
Published
2025-12-23
Last Modified
2026-04-20
Generated
2026-06-16
AI Q&A
2025-12-23
EPSS Evaluated
2026-06-14
NVD
CVE-2025-11419
EUVD
EUVD-2025-36356
Affected Vendors & Products
Showing 2 associated CPEs
Vendor Product Version / Range
redhat keycloak 26.0.16
redhat keycloak 26.2.10
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-770 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.
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Executive Summary

This vulnerability in Keycloak allows an unauthenticated remote attacker to cause a denial of service (DoS) by repeatedly initiating TLS 1.2 client-initiated renegotiation requests. This exhausts the server's CPU resources, making the Keycloak service unavailable. [5]

Impact Analysis

The impact of this vulnerability is a denial of service (DoS) condition where an attacker can exhaust the server's CPU resources by repeatedly initiating TLS renegotiation requests. This makes the Keycloak service unavailable, potentially disrupting authentication and single sign-on services for web, mobile, and RESTful applications relying on Keycloak. [1, 2, 5]

Mitigation Strategies

Immediate mitigation involves configuring Keycloak to reject client-initiated TLS renegotiation by setting the Java system property `-Djdk.tls.rejectClientInitiatedRenegotiation=true` in the Keycloak startup configuration. Additionally, users should back up their existing installations, including applications, configuration files, databases, and settings, and then apply the updated Keycloak packages or container images (version 26.2.10 or 26.0.16) provided by Red Hat to address this vulnerability. [1, 2, 3, 4, 5]

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