Use of cryptographically weak PRNG in the password recovery token generation of Revive Adserver < v4.2.1 causes a potential authentication bypass attack if an attacker exploits the password recovery functionality. In lib/OA/Dal/PasswordRecovery.php, the function generateRecoveryId() generates a password reset token that relies on the PHP uniqid function and consequently depends only on the current server time, which is often visible in an HTTP Date header.
A user having access to the UI of a Revive Adserver instance could be tricked into clicking on a specifically crafted admin account-switch.php URL that would eventually lead them to another (unsafe) domain, potentially used for stealing credentials or other phishing attacks. This vulnerability was addressed in version 4.2.0.