ExpanDrive

Poor, lonely <font>. You were irritating to use, and so you were kicked out of the treehouse in favor of stylesheets by HTML 4.01. But cheer up <font>; you can still be extremely annoying! Just try a Wikipedia vanity search, with a few of your pedantic modifiers thrown in for good measure—let’s use <font face=cursive size=50>:

Not only that, <font>, but your old and even more annoying buddy <table> is back in the game, too. And when you two team up,  there’s almost no limit to the amount of carnage you can create:

This works across browsers, though there are obvious differences in how they render the horribly mangled code these querys will produce. It’s the best lesson in input santization since since Little Bobby Tables.

If you’re good, you can theoretically purpetrate some serious mayhem with this bug—and considering how widely MediaWiki is used around the web, that could be a real problem.

In reality, though, the trickery is probably limited by the abilty of your dirty, dirty inputs to generate search results; without those, it looks like most of your code modifications get cancelled.

That having been said, I endorse using this exploit only for your own personal amusement, not serious destruction. You have been warned.