CVE-2025-11419
TLS Renegotiation DoS Vulnerability in Keycloak Server
Publication date: 2025-12-23
Last updated on: 2026-04-20
Assigner: Red Hat, Inc.
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| redhat | keycloak | 26.0.16 |
| redhat | keycloak | 26.2.10 |
Helpful Resources
Exploitability
| 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. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
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]
How can this vulnerability impact me? :
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]
What immediate steps should I take to mitigate this vulnerability?
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]