PT-2026-32395 · Haproxy+2 · Haproxy+2

Martino Spagnuolo · Published 2026-04-13 · Updated 2026-05-24 · CVE-2026-33555

Positive Technologies (AI Summary)

CVSS v3.1

4.0

Medium

Base vector

AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N

Name of the Vulnerable Software and Affected Versions HAProxy versions 2.6 through 3.3.5

Description The HTTP/3 parser fails to verify that the received body length aligns with a previously announced content-length when a stream is closed using a frame with an empty payload. This discrepancy can lead to desynchronization between the proxy and the backend server, potentially enabling request smuggling, which is a technique used to interfere with the way a website processes sequences of HTTP requests.

Recommendations Update to version 3.3.6 or later.

Exploit

Fix

Weakness Enumeration

CWE-130

Related Identifiers

CVE-2026-33555

OESA-2026-2083

OESA-2026-2084

OESA-2026-2085

OESA-2026-2086

OPENSUSE-SU-2026:10581-1

OPENSUSE-SU-2026:20618-1

RHSA-2026:8749

SUSE-SU-2026:1568-1

SUSE-SU-2026:21280-1

USN-8208-1

Affected Products

Haproxy

Linuxmint

Ubuntu

References · 37

• 🔥 https://r3verii.github.io/cve/2026/04/14/haproxy-h3-standalone-fin-smuggling.html · Exploit
• https://osv.dev/vulnerability/UBUNTU-CVE-2026-33555 · Vendor Advisory
• https://osv.dev/vulnerability/OESA-2026-2086 · Vendor Advisory
• https://osv.dev/vulnerability/DEBIAN-CVE-2026-33555 · Vendor Advisory
• https://osv.dev/vulnerability/SUSE-SU-2026:21280-1 · Vendor Advisory
• https://security-tracker.debian.org/tracker/CVE-2026-33555 · Vendor Advisory
• https://osv.dev/vulnerability/USN-8208-1 · Vendor Advisory
• https://osv.dev/vulnerability/openSUSE-SU-2026:10581-1 · Vendor Advisory
• https://osv.dev/vulnerability/OESA-2026-2083 · Vendor Advisory
• https://osv.dev/vulnerability/SUSE-SU-2026:1568-1 · Vendor Advisory
• https://ubuntu.com/security/notices/USN-8208-1 · Vendor Advisory
• https://osv.dev/vulnerability/openSUSE-SU-2026:20618-1 · Vendor Advisory
• https://ubuntu.com/security/CVE-2026-33555 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-33555 · Security Note
• https://cve.org/CVERecord?id=CVE-2026-33555 · Security Note