The OpenSSL versions bundled in official OpenVPN *Windows installers* prior to 2.3.6-I002/I602 are vulnerable to [FREAK](https://www.smacktls.com/). All users of the official OpenVPN Windows installers are encouraged to upgrade their OpenVPN installations or to take other measures (see below) to mitigate the attack. OpenVPN users on *NIX typically get an updated OpenSSL version through their package management system and do not need to update OpenVPN.

Fortunately the vulnerability's impact on OpenVPN is fairly small:

* If enabled, OpenVPN's tls-auth feature prevents this attack
* Adding *!EXP* to the server side tls-cipher is enough to mitigate attacks. The suggested tls-cipher string is *DEFAULT:!EXP:!LOW:!PSK:!SRP:!kRSA*. This disallows export ciphers, weak ciphers (e.g. DES), and RSA key exchange (note: not RSA authentication), but allows any future, stronger cipher suites.
* Clients who wish to rule out this attack on clients prior to 2.3.6-I002/I603 can add *!kRSA* to their tls-cipher string
* An attacker requires a man-in-the-middle position.
* An attacker has to invest time and money per OpenVPN instance (restart) to attack a connection, which makes this relevant for targeted attacks only.
* OpenVPN always provides PFS with its own key exchange mechanism, making it impossible to decrypt sessions prior to a successful factorization of the temporary export key, even if those connections already used an RSA_EXPORT cipher.