bbPress.org

it is based on a WordPress permission, not bbpress.

Users with HTML Permission will be able to use javascript to do some really horrible things to your site, so as this post says

‘This unfiltered_html permission could be very dangerous in the wrong hands, so please don’t give this permission to any users you do not trust. WordPress has disabled this permission for most users because they rarely need it.’

unfiltered_html

But also shows you how to amend if you want to.