All users of ZoneAlarm Pro 2.6.357 and prior versions: this applies to you!

ZoneAlarm allows users with the same two octets of your IP address to access your computer. Remote users can access the computer running
ZoneAlarm. For example, if your IP address was 203.1.2.3, anyone from 203.1.* could access your computer under the context of your local level security settings. Shocking, no ?

For the full story go to SecuritySearch.