CVE-2024-9666

Service interruption via proxy-header DNS resolution

Published Nov 25, 2024 · Updated Aug 31, 2026

Denial of service in Keycloak before 24.0.9 and 25.0.0 through 26.0.5 allows attackers to exhaust I/O threads via proxy headers. The proxy-header parser accepts non-IP values such as obfuscated identifiers as client addresses and performs costly DNS resolution on them. Exploitation requires accepted proxy headers, a reverse proxy that does not overwrite attacker-supplied values, and, for version 26, HTTP plus the documented hostname and trust conditions.

CVSS severity4.7
Medium
EPSS probability0.40%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Keycloak before 24.0.9 and 25.0.0 through 26.0.5 allows attackers to exhaust I/O threads via proxy headers. The proxy-header parser accepts non-IP values such as obfuscated identifiers as client addresses and performs costly DNS resolution on them. Exploitation requires accepted proxy headers, a reverse proxy that does not overwrite attacker-supplied values, and, for version 26, HTTP plus the documented hostname and trust conditions.

The record

CVE
CVE-2024-9666
Published
Nov 25, 2024
Updated
Aug 31, 2026
Vendor
Red Hat
Product
Red Hat build of Keycloak
Classifications
CWE-444, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Nov 25, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 31, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected versions are unavailable in this record. Check the vendor advisory for version and patch details.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Red Hat · Red Hat build of KeycloakAffected versions are unavailable in this record.
Red Hat · Red Hat build of Keycloak 24Affected versions are unavailable in this record.
Red Hat · Red Hat build of Keycloak 26.0Affected versions are unavailable in this record.
Keycloak · Keycloakversion=0 <24.0.9; version=25.0.0 <26.0.6

Published CVSS scores

4.7KeycloakCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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