#VU56401 Inconsistent interpretation of HTTP requests in HAProxy - CVE-2021-40346
Published: September 8, 2021 / Updated: February 9, 2022
Vulnerability identifier: #VU56401
Vulnerability risk: Medium
CVSSv4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:P/U:Green
CVE-ID: CVE-2021-40346
CWE-ID: CWE-444
Exploitation vector: Remote access
Exploit availability:
Public exploit is available
Vulnerable software:
HAProxy
HAProxy
Software vendor:
HAProxy
HAProxy
Description
The vulnerability allows a remote attacker to preform HTTP request smuggling attacks.
The vulnerability exists due to improper validation of HTTP/2 requests within the htx_add_header() and htx_add_trailer() functions when processing HTTP header name length encoding in the HTX representation. A remote attacker can send a specially crafted HTTP request to the server and smuggle HTTP headers.
Successful exploitation of vulnerability may allow an attacker to poison HTTP cache and perform phishing attacks.
Remediation
Install update from vendor's website.