If I'm not mistaken, CP100/150 runs a Linux/Unix derivative. Haven't heard of or seen any security/vulnerability bullitens released for it yet. As with most "embedded" type applications, things that aren't expressly needed for the system to work are left off.
Marv - if there is a VPN router installed, and CallPilot is on the private side of the VPN router, then it isn't/shouldn't be accessible from the outside world (unless the installer did a really, really bad job configuring the device). In the case of the Contivity platform, there are no default user accounts configured that will terminate a VPN session, and there are no NAT rules configured by default that would "publish" the internal CallPilot IP to the outside world.
Just my 2 cents....