CVE-2026-110354

haproxy: haproxy: Denial of Service via specially crafted HTTP/1.1 chunked request

Published Oct 22, 2026 CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Ubuntu USN Ubuntu USN USN-8972-1 HAProxy vulnerabilities
History
Type Values Removed Values Added
Metrics ssvc

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

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

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

Weaknesses

Sources

Status
PUBLISHED
Assigner
mitre
Published
Updated
Oct 22, 2026, 7:10 PM
Reserved
Oct 13, 2026, 11:22 PM
Status
Awaiting Analysis
Published
Oct 22, 2026, 3:16 AM
Modified
Oct 22, 2026, 7:17 PM
Severity
Important
Public date
Oct 22, 2026, 2:46 AM