Nintendo confirms user accounts were illegally accessed, disables Nintendo Network ID login

Over the past few days, users of Nintendo consoles may have been notified of unrecognized logins on their Nintendo accounts.
According to Nintendo, attackers leveraged Nintendo Network ID (NNID), the login system that was most prominent in the Nintendo 3DS and Wii U era.
As a result of the attack, Nintendo has now disabled the ability to login using an NNID altogether, and it's asking potentially affected users to reset both their NNID and Nintendo account passwords.
If you notice suspicious payments on your account, Nintendo asks that you report it so that the purchases can be cancelled.
Payment information is not included in the information that can be accessed, but as mentioned above, it may be usable on the eShop if your Nintendo account password is the same as the NNID password.