Ingate Firewall 4.1.3 and earlier does not terminate the PPTP session for an active user when the administrator disables that user from a resource, which could allow remote authenticated users to retain unauthorized access to resources.
https://exchange.xforce.ibmcloud.com/vulnerabilities/19123
http://www.securityfocus.com/bid/12383
http://www.ingate.com/relnote-422.php
http://securitytracker.com/id?1013022