If you discover any vulnerability please be aware of the following table of supported versions below. Then feel free to contact me at the email address provided in the bottom of that page.
More details on the Wiki
If you discover any security vulnerability contact me at contact#at#geolim4.com with a subject formatted like that:
[PHPFASTCACHE][VULNERABILITY] Your mail subject goes here
Thanks in advance for taking the time to report me that in private.