#VU52479 Improper authentication in OpenVPN for Windows - CVE-2020-15078
Published: April 21, 2021 / Updated: May 26, 2021
OpenVPN for Windows
OpenVPN
Description
The vulnerability allows a remote attacker to bypass authentication process.
The vulnerability exists due to an error in when processing authentication requests. A remote attacker can bypass authentication and access control channel data on servers configured with deferred authentication, which can be used to potentially trigger further information leaks.
Under certain circumstances an attacker can trick the server using delayed authentication (plugin or management) into returning a PUSH_REPLY before the AUTH_FAILED message, which can possibly be used to gather information about a VPN setup. In combination with "--auth-gen-token" or a user-specific token auth solution it can be possible to get access to a VPN with an otherwise-invalid account.