Since many of us use WHMCS, beware that WHMCS' server was hacked today. Here's a statement from them about it.
Apparently, the hacker was able to obtain WHMCS' entire client database (including details of all who use WHMCS in their hosting businesses), and the hacker plans to post the entire database publicly.
If you have given sensitive details to WHMCS in support tickets, you should change those details ASAP. Credit card numbers may be at risk too, in the event that the hacker gained the encryption key.