CVE-2026-33555CWE-130

CVE-2026-33555

Medium · published April 13, 2026

CVSS v3.1
4.0
EPSS
1%
Percentile
48.3
In the wild
Unconfirmed
What it is

An issue was discovered in HAProxy before 3.3.6. The HTTP/3 parser does not check that the received body length matches a previously announced content-length when the stream is closed via a frame with an empty payload. This can cause desynchronization issues with the backend server and could be used for request smuggling. The earliest affected version is 2.6.

The record
Technical detail
CVSS v3.1
4.0 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N
CVSS v4.0
Not supplied
EPSS
0.00604 · 48.3th percentile
Weakness
CWE-130 · Improper Handling of Length Parameter Inconsistency
Published
2026-04-13T21:16Z
Affected products (1)
ProductVersionsFixed in
haproxy/haproxy≥ 2.6.0, < 3.3.63.3.6
References (7)
https://github.com/haproxy/haproxy/commit/05a295441c621089ffa4318daf0dbca2dd756a84 · [email protected]https://r3verii.github.io/cve/2026/04/14/haproxy-h3-standalone-fin-smuggling.html · [email protected]https://www.haproxy.com/documentation/haproxy-aloha/changelog/ · [email protected]https://www.haproxy.org · [email protected]https://www.mail-archive.com/[email protected]/msg46752.html · [email protected]https://lists.debian.org/debian-lts-announce/2026/10/msg00036.html · af854a3a-2127-422b-91ae-364da2661108https://r3verii.github.io/cve/2026/04/14/haproxy-h3-standalone-fin-smuggling.html · 134c704f-9b21-4f2e-91b3-4a467353bcc0
EPSS history
Timeline
  • 13 APR 00:00Z
    An issue was discovered in HAProxy before 3.3.6
    cvelistv5