Authentication bypass in OpenVPN

1) Improper Authentication

EUVDB-ID: #VU61608

Risk: Medium

CVSSv4.0: 1.7 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2022-0547

CWE-ID: CWE-287 - Improper Authentication

Exploit availability: No

Description

The vulnerability allows a remote attacker to bypass authentication process.

The vulnerability exists due to an error when processing authentication requests in external authentication plug-ins when more than one of them makes use of deferred authentication replies. A remote attacker can bypass authentication process and gain unauthorized access to the network with only partially correct credentials.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

OpenVPN for Windows: 2.1 - 2.5.5

CPE2.3

• cpe:2.3:a:openvpn_net:openvpn:2.1.28.0:*:*:*:*:*:*:*
• cpe:2.3:a:openvpn_net:openvpn:2.2.3:*:*:*:*:*:*:*
• cpe:2.3:a:openvpn_net:openvpn:2.3.18:*:*:*:*:*:*:*
• cpe:2.3:a:openvpn_net:openvpn:2.4.11:*:*:*:*:*:*:*
• cpe:2.3:a:openvpn_net:openvpn:2.5.5:*:*:*:*:*:*:*

External links

https://community.openvpn.net/openvpn/wiki/SecurityAnnouncements
https://community.openvpn.net/openvpn/wiki/CVE-2022-0547

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.