Keycloak TLS Client-Initiated Renegotiation Denial of Service
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.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Java / Kotlin (Maven) | org.keycloak:keycloak-quarkus-dist | < 26.0.16, >= 26.1.0, < 26.2.10, >= 26.3.0, < 26.4.1 | 26.0.16, 26.2.10, 26.4.1 |
References
- https://github.com/keycloak/keycloak/security/advisories/GHSA-q8hq-4h99-fj7x
- https://nvd.nist.gov/vuln/detail/CVE-2025-11419
- https://github.com/keycloak/keycloak/issues/43020
- https://access.redhat.com/errata/RHSA-2025:18254
- https://access.redhat.com/errata/RHSA-2025:18255
- https://access.redhat.com/errata/RHSA-2025:18889
- https://access.redhat.com/errata/RHSA-2025:18890
- https://access.redhat.com/security/cve/CVE-2025-11419
- https://bugzilla.redhat.com/show_bug.cgi?id=2402142
- https://github.com/keycloak/keycloak
- https://github.com/keycloak/keycloak/discussions/25209
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H- Weakness (CWE)
CWE-400, CWE-770- Platform
- Java / Kotlin (Maven)
- Package
org.keycloak:keycloak-quarkus-dist- Disclosed
- 27.10.2025
- Updated
- 11.10.2026 12:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-q8hq-4h99-fj7x - CC BY 4.0
Vulnerability history: org.keycloak:keycloak-quarkus-dist
All published vulnerabilities of this package (Java / Kotlin (Maven)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 2
- First → latest
- 10.2025 12.2025
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 1
- Medium 1
Disclosures per year
- 2025: 2
- 2026: 0
-
Keycloak TLS Client-Initiated Renegotiation Denial of Service this entry
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