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MEDIUM severity

Denial of Service in Keycloak Server via Security HeadersGHSA-w3g8-r9gw-qrh8

MEDIUMFix: keycloak/keycloak@93b2a73

GHSA-w3g8-r9gw-qrh8 is a medium-severity (CVSS 6.5) CWE-693 vulnerability in org.keycloak:keycloak-quarkus-server. A fix is available for org.keycloak:keycloak-quarkus-server — see the affected versions and patch details below.

Also known asCVE-2024-11734
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 3, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for GHSA-w3g8-r9gw-qrh8.

EPSS Exploitation Probability

via FIRST.org ↗
0.9%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs61th percentile — riskier than 61% of all scored CVEsHighest risk
0.00%0.48%0.97%1.45%0.0%0.9%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected
☕org.keycloak:keycloak-quarkus-server

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

Description

A potential Denial of Service (DoS) vulnerability has been identified in Keycloak, which could allow an administrative user with the rights to change realm settings to disrupt the service. This is done by modifying any of the security headers and inserting newlines, which causes the Keycloak server to write to a request that is already terminated, leading to a failure of said request.

Service disruption may happen, users will be unable to access applications relying on Keycloak, or any of the consoles provided by Keycloak itself on the affected realm.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
☕Mavenorg.keycloak:keycloak-quarkus-serverall versions26.0.8org.keycloak:keycloak-quarkus-server:26.0.8

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.keycloak:keycloak-quarkus-server, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update org.keycloak:keycloak-quarkus-server to 26.0.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-w3g8-r9gw-qrh8 is resolved across your whole dependency graph.

  3. Workarounds

    Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

Red Hat has evaluated this vulnerability and its impact is restricted to Keycloak. No Keycloak connectors/adapters are affected.

Workaround published by Red Hat
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.
Source: Red Hat security advisory for GHSA-w3g8-r9gw-qrh8 (CC BY 4.0)
ProductFixed inAdvisory
Red Hat build of Keycloak 26.0rhbk/keycloak-operator-bundle:26.0.8-1RHSA-2025:0299
RHBK 26.0.8see advisoryRHSA-2025:0300

Frequently Asked Questions

A potential Denial of Service (DoS) vulnerability has been identified in Keycloak, which could allow an administrative user with the rights to change realm settings to disrupt the service. This is done by modifying any of the security headers and inserting newlines, which causes the Keycloak server to write to a request that is already terminated, leading to a failure of said request. Service disruption may happen, users will be unable to access applications relying on Keycloak, or any of the consoles provided by Keycloak itself on the affected realm.
O3 Security · Impact-Aware SCA

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Denial of Service in Keycloak Server via Security Headers