MPGH
In October 2015, the multiplayer game hacking website MPGH was hacked and 3.1 million user accounts disclosed. The vBulletin forum breach contained usernames, email addresses, IP addresses and salted hashes of passwords.
A security/data breach is the intentional or unintentional security incident in which information was accessed without authorization. Release of secure or private/confidential information to public can hurt businesses and consumers in a many of ways.
Other reference: security compromise, data leak, information disclosure, information leakage, data spill.
List of all known breaches.