WHMCS has released a new update for all supported versions of WHMCS. This update contains a change that addresses a specific security concern within the WHMCS product.
We strongly encourage you to update your WHMCS installations as soon as possible.
WHMCS has rated this update as having an important security impact. Information on security ratings can be found at http://docs.whmcs.com/Security_Levels
Please update your installation to the following version:
Patches - What is a Patch?
Read more @ http://blog.whmcs.com/?t=83303