CVE-2024-11734: Org.keycloak:keycloak-quarkus-server: denial of service in keycloak server via security headers

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.9% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-01-14 · updated 2026-08-31
Weakness: CWE-693

Description

A denial of service vulnerability was found in Keycloak that could allow an administrative user with the right to change realm settings to disrupt the service. This action is done by modifying any of the security headers and inserting newlines, which causes the Keycloak server to write to a request that has already been terminated, leading to the failure of said request.

Affected products

Red Hat build of Keycloak 26.4: all versions — fixed in 26.0-7, 26.0-8, 26.0.8-1

How to fix

Upgrade to a fixed version: Red Hat build of Keycloak 26.4 26.0-7, 26.0-8, 26.0.8-1. Check the vendor advisory for mitigations.

References

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