Bug 2402142 (CVE-2025-11419)

Summary: CVE-2025-11419 keycloak: Keycloak TLS Client-Initiated Renegotiation Denial of Service
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: aschwart, boliveir, mposolda, pjindal, ssilvert, sthorger, vmuzikar
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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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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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2025-10-07 11:17:03 UTC 
Keycloak is vulnerable to a Denial of Service (DoS) attack due to the default JDK setting that permits Client-Initiated Renegotiation in TLS 1.2. An unauthenticated remote attacker can repeatedly initiate TLS renegotiation requests to exhaust server CPU resources, making the service unavailable. Immediate mitigation is available by setting the -Djdk.tls.rejectClientInitiatedRenegotiation=true Java system property in the Keycloak startup configuration.

Requirements to exploit

An attacker requires network access to any TLS-enabled endpoint on a Keycloak server. No authentication is required to launch the attack.