CVE-2026-110354CWE-835

CVE-2026-110354

High · published October 22, 2026

CVSS v3.1
7.5
EPSS
1%
Percentile
54.9
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
7.5 · HIGH
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS v4.0
Not supplied
EPSS
0.00762 · 54.9th percentile
Weakness
CWE-835 · Loop with Unreachable Exit Condition ('Infinite Loop')
Published
2026-10-22T07:16Z
References (1)
https://git.haproxy.org/?p=haproxy.git;a=commit;h=077906da140a35873bf451d7e9f67646c9f37c81 · [email protected]
EPSS history
Timeline
  • 23 OCT 03:55Z
    EPSS moved — → 1%
    epss
  • 22 OCT 02:46Z
    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…
    cvelistv5
  • 22 OCT 02:46Z
    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…
    cvelistv5