The Wii U Kernel exploit for 5.5 that has been left right and center of discussions on the Wii U scene recently, was just leaked a couple of hours ago on GBATemp. This exploit lets you run Loadiine (Wii U backup launcher), Cafiine, and a bunch of other cool tools. The exploit is compatible with (at least) firmwares 5.5.0 and 5.5.1
Developer @NWPlayer1234, one of the people behind the exploit (along with Marionumber1) has confirmed the leak is the real thing. It’s a full fledged exploit and people have already been confirming they can run Loadiine and other tools with it.
The leak happens a few days after NWPlayer1234 “suggested” someone leaked the exploit. It turns out one of the exploit’s handful of beta testers who had access to the file probably took the suggestion a bit too seriously.