#VU55969 Input validation error in HAProxy - CVE-2021-39240
Published: August 18, 2021
Vulnerability identifier: #VU55969
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-2021-39240
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 security restrictions.
The vulnerability exists due to insufficient validation of user-supplied input when processing HTTP/2 requests. HAProxy does not ensure that the scheme and path portions of a URI have the expected characters, e.g. the authority field on a target HTTP/2 server might differ from what the routing rules were intended to achieve.
A remote attacker can send specially crafted input to the application and bypass implemented security restrictions.
Remediation
Install updates from vendor's website.