The Wii U was one of the least popular platforms by Nintendo. It never saw much sales, probably partly due to its confusing name and its strange ‘not-a-tablet’ controller.
I still own one. I have Mario Kart for it. When I got a Nintendo Switch some years later, it had the same Mario Kart game ported to it; I never bought that edition because I already had the Wii U edition.
Today for the first time in months I felt like playing Mario Kart again, and I started the game. Out of curiosity, I wanted to check if Mario Kart Online was still going. I got a message that online play was temporarily not available due to maintenance. I thought “oh I guess they must have ended support for online mode now”, after all the console was not a top seller and is over 10 years old now and its successor the Nintendo Switch sold almost 10 times more units.
However, after searching online, that does not seem to be the full truth (The Verge article). It turns out there is a vulnerability part of a networking library used in many first party Nintendo games on Switch, Wii U, and 3DS, for which an exploit is available, which caused Nintendo to release fixes for many titles and turn off online capability for Mario Kart 8 on Wii U.
It seems the vulnerability is called ENLBufferPwn and it allows for an attacker to execute arbitrary code on their victims device, which is really nasty, especially given the Wii U and the 3DS are equipped with camera and microphones which then also potentially be used by said attacker.
I think it’s kind of strange to see that, according to the GitHub page linked above, Nintendo’s actions to patch the game spread over multiple months: Mario Kart 8 for Switch was fixed in version 2.1.0 which is dated August 4th 2022, Splatoon 3 got fixed in late 2022, and only on the 3rd of March 2023 Nintendo decided to turn off the game servers for Mario Kart 8 for Wii U. That is almost 8 months after releasing the fix for the Switch version!
Also, the Nintendo Network Maintenance Page shows that the server is in maintenance and Nintendo “has no information on when network services can be restored“… and this is already 10 weeks ago now. I’m curious to see if the service will come back at some point. Also, I would be interested to find out why it’s taking Nintendo such a long time to roll out patches for an error in a library they used in many of their games!