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Fencer Vulns
high 7.5

CVE-2026-110354 json

HAProxy 3 before 3.4.6 allows a remote unauthenticated attacker to cause a denial of service (persistent worker-thread CPU exhaustion) via…

published 2026-10-22 18 d ago modified 2026-10-22 17 d ago also EUVD-2026-108000

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.8%
EPSS 0.8% chance of exploitation in 30 days, percentile 57%
public exploits
0
none known

Summary

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.

Patch / fix

  • HAProxy HAProxy 3.0.30, 3.2.26, 3.3.17, 3.4.6, 3.5-dev9
  • HAProxy HAProxy Enterprise Edition 3.0r1-362.1441, 3.2r1-378.1259, 3.3r1-377.1005
  • HAProxy Technologies HAProxy Kubernetes Ingress Controller 3.2.17
  • HAProxy Technologies Kubernetes Ingress Controller Enterprise 1.11.14-ee11, 3.0.16-ee17, 3.2.17-ee1
  • haproxy Debian 12 2.6.12-1+deb12u4
  • haproxy Debian 13 3.0.11-1+deb13u4
  • haproxy Debian 14 3.2.26-1

debian advisories DEBIAN-CVE-2026-110354

  • haproxy Ubuntu 22.04 LTS 2.4.30-0ubuntu0.22.04.3
  • haproxy Ubuntu 24.04 LTS 2.8.30-0ubuntu0.24.04.2
  • haproxy Ubuntu 26.10 3.4.2-1ubuntu4.1
  • haproxy Ubuntu 26.04 LTS 3.2.25-0ubuntu0.26.04.2

ubuntu advisories UBUNTU-CVE-2026-110354

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • haproxy openSUSE Tumbleweed 3.4.7+git57.0faeaeda6-2.1

opensuse advisories openSUSE-SU-2026:12431-1

  • haproxy Azure Linux 3.0 2.9.11-9

azure linux advisories AZL-111017

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-110354 updated cvss 7.5

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

  • Red Hat Ceph Storage 5 haproxy, haproxy22
    affected: no fix available “Fix deferred”
  • Red Hat Enterprise Linux 7 haproxy Red Hat Enterprise Linux 8 haproxy Red Hat Enterprise Linux 9 haproxy Red Hat OpenShift Container Platform 4 haproxy, haproxy18, haproxy20, haproxy22, haproxy26, haproxy28 Red Hat OpenShift Container Platform 5 haproxy, haproxy32 3.2.22-1.rhocp.el9
    affected: no fix available
  • Red Hat Hardened Images haproxy 3.0.30-0.1.hum1
    fixed: vendor fix RHSA-2026:83844
  • Red Hat Enterprise Linux 10 haproxy
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
18 d ago

Exploit prediction

0.81% chance of exploitation in the next 30 days, higher than 57% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

  • HAProxy HAProxy
  • HAProxy HAProxy Enterprise Edition
  • HAProxy Technologies HAProxy Kubernetes Ingress Controller
  • HAProxy Technologies Kubernetes Ingress Controller Enterprise

Classification

Weakness
  • CWE-835 Loop with Unreachable Exit Condition

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.