Re: Forums...VB Vs. IPB
All CMS and Forum system(forums stores content, so it's a cms) have the same security loopholes.
A common example, the XSS in the forum descriptions, anyone can get into the admin panel and steal all the users cookies, sites visited, and much more, and the users won't even know it.
But, I would suggest vBulletin, even though it's a paid product, it is the money worths.
The team of very experienced developers made it, and maintains it.