Open Newsletter 2.5 and earlier allows remote authenticated administrators to execute arbitrary PHP code by inserting the code into the email parameter to (1) subscribe.php or (2) unsubscribe.php.

The (1) settings.php and (2) subscribers.php scripts in Open Newsletter 2.5 and earlier do not exit when authentication fails, which allows remote attackers to perform unauthorized administrative actions, or execute arbitrary code in conjunction with another vulnerability.