HAProxy 3 before 3.4.6 allows a remote unauthenticated attacker to cause a denial of service (persistent worker-thread CPU exhaustion) via an HTTP/1.1 chunked request. Although the H1 multiplexer drains the request before closing the stream, the parser repeatedly re-processes the same bytes without making progress. The affected thread stays busy at 100% CPU after timeouts expire and after the client disconnects, and repeated requests can consume all worker threads until the process is restarted.

Metrics

No CVSS v4.0

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploitation none

Automatable yes

Technical Impact partial

Affected Vendors & Products

Vendors Products
Haproxy
  • Haproxy
  • Haproxy Enterprise
  • Kubernetes Ingress Controller
  • Kubernetes Ingress Controller Enterprise

No data.

No data.

References
Link Providers
https://git.haproxy.org/?p=haproxy.git;a=commit;h=077906da140a35873bf451d7e9f67646c9f37c81 cve-icon cve-icon cve-icon
https://nvd.nist.gov/vuln/detail/CVE-2026-110354 cve-icon
https://www.cve.org/CVERecord?id=CVE-2026-110354 cve-icon
History

Fri, 23 Oct 2026 00:45:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Thu, 22 Oct 2026 12:30:00 +0000

Type Values Removed Values Added
Title Remote Denial of Service via HTTP Chunked Request in HAProxy haproxy: haproxy: Denial of Service via specially crafted HTTP/1.1 chunked request
References
Metrics threat_severity

None

 threat_severity

Important

Thu, 22 Oct 2026 11:00:00 +0000

Type Values Removed Values Added
First Time appeared Haproxy
Haproxy haproxy
Haproxy haproxy Enterprise
Haproxy kubernetes Ingress Controller
Haproxy kubernetes Ingress Controller Enterprise
Vendors & Products Haproxy
Haproxy haproxy
Haproxy haproxy Enterprise
Haproxy kubernetes Ingress Controller
Haproxy kubernetes Ingress Controller Enterprise

Thu, 22 Oct 2026 06:00:00 +0000

Type Values Removed Values Added
Title Remote Denial of Service via HTTP Chunked Request in HAProxy

Thu, 22 Oct 2026 03:00:00 +0000

Type Values Removed Values Added
Description HAProxy 3 before 3.4.6 allows a remote unauthenticated attacker to cause a denial of service (persistent worker-thread CPU exhaustion) via an HTTP/1.1 chunked request. Although the H1 multiplexer drains the request before closing the stream, the parser repeatedly re-processes the same bytes without making progress. The affected thread stays busy at 100% CPU after timeouts expire and after the client disconnects, and repeated requests can consume all worker threads until the process is restarted.
Weaknesses CWE-835
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}
cve-icon MITRE

Status: PUBLISHED

Assigner: mitre

Published: 2026-10-22T02:46:38.255Z

Updated: 2026-10-22T19:10:34.563Z

Reserved: 2026-10-13T23:22:44.319Z

Link: CVE-2026-110354

cve-icon Vulnrichment

Updated: 2026-10-22T19:01:03.356Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-10-22T03:16:31.427

Modified: 2026-10-22T19:17:35.660

Link: CVE-2026-110354

cve-icon Redhat

Severity : Important

Publid Date: 2026-10-22T02:46:38Z

Links: CVE-2026-110354 - Bugzilla