#VU126147 Inconsistent interpretation of HTTP requests in HAProxy - CVE-2026-33555
Published: April 15, 2026
Vulnerability identifier: #VU126147
Vulnerability risk: Medium
CVSSv4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-33555
CWE-ID: CWE-444
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerable software:
HAProxy
HAProxy
Software vendor:
HAProxy
HAProxy
Description
The vulnerability allows a remote attacker to perform HTTP request smuggling attacks.
The vulnerability exists due to improper validation of HTTP/3 requests. A remote attacker can send a specially crafted HTTP/3 request to the server and smuggle arbitrary HTTP headers.
Successful exploitation of vulnerability may allow an attacker to poison HTTP cache and perform phishing attacks.
Remediation
Install updates from vendor's website.