Nintendo has apologised for leaving Mario Kart 8 and Splatoon on Wii U without online play since March, as it brings servers for both games back online.

In a statement released today, five months after it temporarily shut down online multiplayer for both titles, Nintendo says it has addressed a "vulnerability related to online play".

Servers will go live again sometime tomorrow, 3rd August, some 153 days later, with a fresh patch to download for both Mario Kart 8 and Splatoon.

Nintendo's statement on the downtime, released this morning, is the first confirmation we've had that the games were affected by a security issue.

Back in March, reliable Nintendo dataminer OatmealDome suggested the likely cause was ENLBufferPwn, a common vulnerability present in several first-party Nintendo games which could allow a hacker to remotely execute code.

At the time, Nintendo simply warned that Mario Kart 8 and Splatoon servers had been disabled for "an extended maintenance duration", without going into specifics.

"Please accept our sincere apologies for the extended waiting period," Nintendo said today.

"If further issues occur which make it difficult to continue supporting online play, we may have to discontinue the online play service for the Wii U games Splatoon and Mario Kart 8 at short notice. Should this occur, please note that offline play would continue to function normally.

"Thank you for your patience and understanding."

Servers for Mario Kart 8 Deluxe and Splatoon 3 on Nintendo Switch have remained unaffected.