CVE-2026-55203

HAProxy through 3.4.0, fixed in commit 5985276, contains an integer overflow vulnerability in the fcgi_conn structure's drl field that allows buffer misparse as new FCGI record headers. When contentLength is 65535 and paddingLength is 1 or more, the drl field wraps to 0, causing incorrect record consumption and allowing malicious FastCGI backends to desynchronize the FCGI framing parser, potentially causing request routing errors, response smuggling, or memory safety issues.

CVSS v3 7.5 HIGH

7.5^/10

CVSS v3 : HIGH

Vector :

Exploitability : 2.2 / Impact : 4.7

Attack Vector NETWORK

Attack Complexity HIGH

Privileges Required NONE

User Interaction NONE

Confidentiality Impact LOW

Integrity Impact HIGH

Availability Impact NONE

Scope CHANGED

References

Link	Resource
https://github.com/haproxy/haproxy/commit/5985276735777634d8c85f1d73bb7764aab0d6dd	Patch
https://www.vulncheck.com/advisories/haproxy-integer-overflow-in-fcgi-demux-record-length-field	Third Party Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:haproxy:haproxy:*:*:*:*:*:*:*:*

History

26 Jun 2026, 02:47

Type	Values Removed	Values Added
CPE		cpe:2.3:a:haproxy:haproxy::::::::
References	~~() https://github.com/haproxy/haproxy/commit/5985276735777634d8c85f1d73bb7764aab0d6dd -~~	() https://github.com/haproxy/haproxy/commit/5985276735777634d8c85f1d73bb7764aab0d6dd - Patch
References	~~() https://www.vulncheck.com/advisories/haproxy-integer-overflow-in-fcgi-demux-record-length-field -~~	() https://www.vulncheck.com/advisories/haproxy-integer-overflow-in-fcgi-demux-record-length-field - Third Party Advisory
First Time		Haproxy Haproxy haproxy

18 Jun 2026, 17:16

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-06-18 17:16

Updated : 2026-07-14 22:17

NVD link : CVE-2026-55203

Mitre link : CVE-2026-55203

CVE.ORG link : CVE-2026-55203

JSON object : View

Products Affected

haproxy

haproxy

CWE

CWE-190

Integer Overflow or Wraparound

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