CVE-2026-110354
Publication date 22 October 2026
Last updated 3 November 2026
Ubuntu priority
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.
Status
| Package | Ubuntu Release | Status |
|---|---|---|
| haproxy | 26.10 stonking |
Fixed in 3.4.2-1ubuntu4.1
|
| 26.04 LTS resolute |
Fixed in 3.2.25-0ubuntu0.26.04.2
|
|
| 24.04 LTS noble |
Fixed in 2.8.30-0ubuntu0.24.04.2
|
|
| 22.04 LTS jammy |
Fixed in 2.4.30-0ubuntu0.22.04.3
|
|
| 20.04 LTS focal |
Needs evaluation
|
|
| 18.04 LTS bionic |
Needs evaluation
|
|
| 16.04 LTS xenial |
Needs evaluation
|
Patch details
Severity score breakdown
CVSS version: CVSS v3.0
Base score
7.5 · High
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
References
Related Ubuntu Security Notices (USN)
- USN-8972-1
- HAProxy vulnerabilities
- 3 November 2026