Jailbreakers are always on the prowl to knock down or bypass the digital rights management systems or anti-piracy lockdown measures that are incorporated by gaming companies in a bid to only allow cryptographically signed games to run on their gaming consoles. Hackers exploit in-game vulnerabilities or bugs present in the operating system of gaming consoles themselves to defeat these security measures.
According to wiiuhacks.com, the hack allows users to play pirated copies of games as well as run unauthorized software on the Wii U. The hack is the one that worked on old Wii systems and is claimed to be working on the Wii U when it is run in legacy Wii mode. The site also has a list of games through which the exploit can be executed on the Wii U.
The Wii U hackers have also posted a video that showcases their hack. In the video, the hackers are executing the "Smash Stack" exploit from a game disc following which they are shown playing homebrew games on the Wii U. The probable reason that the exploit of old Wii console would have worked on the new console is that the Wii U is backwards compatible with most Wii games and accessories.
Nintendo has released an update just a day after the release of Wii U. It has warned users not to interrupt the update process and asked users not to power down or unplug their Wii U systems while updates are being downloaded as it may brick their device.
“Wii U owners, please do not power down or unplug your system while downloading updates. Doing so may cause damage to your Wii U.” reads a tweet from Nintendo.