# CVE-2024-9666: Org.keycloak/keycloak-quarkus-server: keycloak proxy header handling denial-of-service (dos) vulnerability

Status: published. Published: 2024-11-25. Updated: 2026-11-03.

A vulnerability was found in the Keycloak Server. The Keycloak Server is vulnerable to a denial of service (DoS) attack due to improper handling of proxy headers. When Keycloak is configured to accept incoming proxy headers, it may accept non-IP values, such as obfuscated identifiers, without proper validation. This issue can lead to costly DNS resolution operations, which an attacker could exploit to tie up IO threads and potentially cause a denial of service.
The attacker must have access to send requests to a Keycloak instance that is configured to accept proxy headers, specifically when reverse proxies do not overwrite incoming headers, and Keycloak is configured to trust these headers.

## Remediation

- workaround: Configure the reverse proxy to overwrite incoming proxy headers, including X-Forwarded-For, and ensure Keycloak trusts proxy headers only from the intended proxy rather than directly from untrusted clients. If proxy-header support is not required, disable acceptance of incoming proxy headers. (source: CNA: redhat)

## Affected products and versions

-  /  (keycloak): ≥ 0; < 24.0.9 (affected, semver); ≥ 25.0.0; < 26.0.6 (affected, semver). Source: CNA: redhat
- Red Hat / Red Hat build of Keycloak 24 (rhbk/keycloak-operator-bundle): ≥ 24.0.9-1; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat build of Keycloak 24 (rhbk/keycloak-rhel9): ≥ 24-18; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat build of Keycloak 24 (rhbk/keycloak-rhel9-operator): ≥ 24-18; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat build of Keycloak 24.0.9: Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat build of Keycloak 26.0 (rhbk/keycloak-operator-bundle): ≥ 26.0.6-2; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat build of Keycloak 26.0 (rhbk/keycloak-rhel9): ≥ 26.0-5; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat build of Keycloak 26.0 (rhbk/keycloak-rhel9-operator): ≥ 26.0-6; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat build of Keycloak 26.0.6: Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Build of Keycloak (keycloak-quarkus-server): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat JBoss Enterprise Application Platform 8 (keycloak-quarkus-server): Version range not reported. Source: CNA: redhat

## Severity and prioritization

- CVSS 3.1: 4.7 (medium); CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H; source: CNA: redhat

- CISA KEV: No listing in collected sources

- EPSS: 0.40% as of 2026-11-02; percentile 34.52%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-444

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://access.redhat.com/errata/RHSA-2024:10175 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2024:10176 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2024:10177 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2024:10178 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/security/cve/CVE-2024-9666 (CNA: redhat; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2317440 (CNA: redhat; issue-tracking, x_refsource_REDHAT)

## Provenance

- CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2024-9666; retrieved 2026-11-03; source updated 2026-11-03

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2024-9666; retrieved 2026-11-03; source updated Not reported

Revision: a68857133dbe28d343db79838cc8ba06be51c3a43d42ecec0e0be52c030ffb78

Canonical: https://y2.dev/cve/CVE-2024-9666

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