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

Description

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.

Timeline

Scores

EPSS (exploitation in 30 days)

0.40% · top 65% of all CVEs (11 Nov 2026)

CISA SSVC

Exploitation: none · Automatable: no · Technical impact: partial

The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 4.7.

Affected products

• keycloak

  • affected < 24.0.9
  • affected 25.0.0 – < 26.0.6

• Red Hat · Red Hat build of Keycloak 24

  • unaffected 24.0.9-1 – < *

• Red Hat · Red Hat build of Keycloak 24

  • unaffected 24-18 – < *

• Red Hat · Red Hat build of Keycloak 24

  • unaffected 24-18 – < *

• Red Hat · Red Hat build of Keycloak 24.0.9

  All versions: unaffected

• Red Hat · Red Hat build of Keycloak 26.0

  • unaffected 26.0.6-2 – < *

• Red Hat · Red Hat build of Keycloak 26.0

  • unaffected 26.0-5 – < *

• Red Hat · Red Hat build of Keycloak 26.0

  • unaffected 26.0-6 – < *

• Red Hat · Red Hat build of Keycloak 26.0.6

  All versions: unaffected

• Red Hat · Red Hat Build of Keycloak

  All versions: affected

• Red Hat · Red Hat JBoss Enterprise Application Platform 8

  All versions: unaffected

Affected packages

From reviewed advisories of the GitHub Advisory Database.

• Mavenorg.keycloak:keycloak-quarkus-serverGHSA-jgwc-jh89-rpgq (opens in a new tab)

What to do

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.

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• EUVD EUVD-2024-3365 (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisory GHSA-jgwc-jh89-rpgq (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2024-9666](https://cveledger.app/badge/CVE-2024-9666.svg)](https://cveledger.app/cve/CVE-2024-9666)

Record last updated 3 Nov 2026, 09:30 UTC.