Hackers have developed an exploit of known vBulletin vulnerability, that can be used to add a user remotely to a user to an admin panel with admin privileges. Hundreds of major websites have been reported to be affected by the exploit. Hackers targeting Pakistani forums, as well as some USA based forums also i.e. Pakistan, USA and India. Users advised to upgrade to the latest version to fix the issue. The exploit is not quite clear the extent of the exploit, however, it isn’t quite clear how many websites are affected.
Source: https://thehackernews.com/2013/09/major-vbulletin-based-websites-are.html