CVE-2023-0836: Haproxy

High severity, CVSS 7.5. EPSS: 1.2% chance of exploitation in the next 30 days.

An information leak vulnerability was discovered in HAProxy 2.1, 2.2 before 2.2.27, 2.3, 2.4 before 2.4.21, 2.5 before 2.5.11, 2.6 before 2.6.8, 2.7 before 2.7.1. There are 5 bytes left uninitialized in the connection buffer when encoding the FCGI_BEGIN_REQUEST record. Sensitive data may be disclosed to configured FastCGI backends in an unexpected way.

Affected products

• Haproxy Haproxy: from 2.2.0, before 2.2.27 (fixed in 2.2.27); from 2.4.0, up to and including 2.4.21; from 2.5.0, up to and including 2.5.11; from 2.6.0, up to and including 2.6.8; version 2.1.0 only; version 2.3.0 only; …

Published 2023-03-29. Last modified 2026-06-17.