Obviously I am not going to post the entire change log from Virtualizer 2.3.1, however they seem to react fast to security related issues and they do give credit where credit is due:
You can read the entire thing here: http://www.virtualizor.com/blog/1) [Critical Bug Fix] We would like to thank Safe Or Not and Rack911 for reporting the issues. These are critical bug fixes and we recommend all users to upgrade immediately.