Japan's Club Nintendo service was hacked following thousands of unauthorized accesses across the last month. Nintendo announced that an internal investigation confirmed just under 24,000 illegitimate logins between June 9 and July 4, from over 15 million attempts.
As translated by Kotaku
, Nintendo said customer information compromised in the attack includes full names, phone numbers, and home and email addresses. Happily, the service doesn't hold credit card information. Kotaku notes the attack is apparently limited to Japan's Club Nintendo, and other countries don't seem to be affected.
Unsurprisingly, Nintendo is strengthening Club Nintendo's security as a result, starting off with making users' old passwords invalid and requiring them to make new ones.