WHMCS has released new updates for all supported versions of WHMCS. These updates include changes that address security concerns within the WHMCS product.
WHMCS has rated these updates as having a moderate to important security impact. Information on security ratings can be found at http://docs.whmcs.com/Security_Levels
Please update your installation to the latest version 5.3.9.
This update includes significant changes to IP detection logic in conjunction with the use of proxies. If using...
Read more @ http://blog.whmcs.com/?t=92542