#VU55970 Input validation error in HAProxy - CVE-2021-39241
Published: August 18, 2021
Vulnerability identifier: #VU55970
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:U/U:Green
CVE-ID: CVE-2021-39241
CWE-ID: CWE-20
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 bypass implemented security restrictions.
The vulnerability exists due to insufficient validation of user-supplied input in HAProxy. An HTTP method name may contain a space followed by the name of a protected resource. It is possible that a server would interpret this as a request for that protected resource, such as in the "GET /admin? HTTP/1.1 /static/images HTTP/1.1" example.
The attacker can abuse such behavior to bypass implemented security restrictions and perform unauthorized actions against the web application behind the HAProxy.
Remediation
Install updates from vendor's website.