Redmine

I think this is a have-your-cake-and-eat-it-too scenario. Issue descriptions are textilized so they can be formatted, and part of that is accepting HTML as-is. You should probably put any HTML in the descriptions (that you don't want interpreted by browsers) into a

Actually, HTML is escaped here on redmine.org (eg. <h1>Redmine</h1>) except pre tags used for preformatted text.
I'll commit this change.