Youtube:
https://www.youtube.com/watch?v=C84Z2yCGKAE
A security issue has been reported to us that affects the versions of vBulletin listed here: 5.0.4, 5.0.5, 5.1.0, 5.1.1, and 5.1.2 We have released security patches to account for this vulnerability. The issue may allow attackers to perform SQL injection attacks on your database. It is recommended that all users update as soon as possible.
You can download the patch for your version here: http://members.vbulletin.com/patches.php