OpenVPN 2.1 until v2.4.12 and v2.5.6 may enable authentication bypass in external authentication plug-ins when more than one of them makes use of deferred authentication replies, which allows an external user to be granted access with only partially correct credentials.
| Software | From | Fixed in |
|---|---|---|
| openvpn / openvpn | 2.5.0 | 2.5.6 |
| openvpn / openvpn | 2.1.0 | 2.4.12 |
| fedoraproject / fedora | 34 | 34.x |
| fedoraproject / fedora | 36 | 36.x |
| debian / debian_linux | 9.0 | 9.0.x |