OpenVPN Connect 3.1.0.361 on Windows has Insecure Permissions for %PROGRAMDATA%\OpenVPN Connect\drivers\tap\amd64\win10, which allows local users to gain privileges by copying a malicious drvstore.dll there.

OpenVPN, when using a 64-bit block cipher, makes it easier for remote attackers to obtain cleartext data via a birthday attack against a long-duration encrypted session, as demonstrated by an HTTP-over-OpenVPN session using Blowfish in CBC mode, aka a "Sweet32" attack.

Weak encryption algorithm in Easy-RSA version 3.0.5 through 3.1.7 allows a local attacker to more easily bruteforce the private CA key when created using OpenSSL 3

OpenVPN ovpn-dco for Windows version 1.1.1 allows an unprivileged local attacker to send I/O control messages with invalid data to the driver resulting in a NULL pointer dereference leading to a system halt.

OpenVPN Connect before version 3.5.0 can contain the configuration profile's clear-text private key which is logged in the application log, which an unauthorized actor can use to decrypt the VPN traffic

OpenVPN before 2.6.11 does not santize PUSH_REPLY messages properly which attackers can use to inject unexpected arbitrary data into third-party executables or plug-ins.

OpenVPN from 2.6.0 through 2.6.10 in a server role accepts multiple exit notifications from authenticated clients which will extend the validity of a closing session

tap-windows6 driver version 9.26 and earlier does not properly check the size data of incomming write operations which an attacker can use to overflow memory buffers, resulting in a bug check and potentially arbitrary code execution in kernel space

OpenVPN plug-ins on Windows with OpenVPN 2.6.9 and earlier could be loaded from any directory, which allows an attacker to load an arbitrary plug-in which can be used to interact with the privileged OpenVPN interactive service.

The interactive service in OpenVPN 2.6.9 and earlier allows an attacker to send data causing a stack overflow which can be used to execute arbitrary code with more privileges.