Vulnerability identifier: #VU52479
Vulnerability risk: Medium
CVSSv3.1: 7.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N/E:U/RL:O/RC:C]
CVE-ID:
CWE-ID:
CWE-287
Exploitation vector: Network
Exploit availability: No
Vulnerable software:
OpenVPN
Server applications /
Remote access servers, VPN
Vendor: openvpn.net
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.
Mitigation
Install updates from vendor's website.
Vulnerable software versions
OpenVPN: 2.4.0 - 2.4.10, 2.5.0 - 2.5.1
External links
http://github.com/OpenVPN/openvpn/releases/tag/v2.4.11
http://github.com/OpenVPN/openvpn/releases/tag/v2.5.2
http://community.openvpn.net/openvpn/wiki/CVE-2020-15078
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.