Hundreds of NNID accounts hacked. Change your passwords!

fantanoice

I can see through time
Pronouns
She / They
https://mynintendonews.com/2017/01/23/warning-around-450-nintendo-network-accounts-have-been-hacked/
 
Wasn't on the list but I changed my password and deleted my credit card info from the eshop anyway. I suggest doing the same.
 
comment from the reddit thread linked on the post in the OP:

It's not a direct hack on Nintendo Network. Months ago hackers leaked a large user list from Nugget Bridge, a website where competitive Pokémon (VGC) players gather (or gathered, the website has been quite inactive since the hack). Someone decided to test the usernames and passwords on Nintendo Network, I guess these 450 are the ones who worked. If you examine the list will notice a lot of the compromised users end in "VGC".

The leaker commented here explaining better what happened.

The lesson here is, don't use the same user and the same password for different sites.
 
Back