The LinuxForums.org data plug is a event of the forums using an old version of vBulletin (version 4.2.2, released back in october 2013), a proprietary Internet forum software. Along with the 276k unique email addresses, usernames, IP addresses and salted MD5 password hashes were also leaked. Using salted MD5 password hashes is a bad idea because... well, MD5 is very fast, so an assailant canful try billions of password combinations per second. The HackNotice security research team discovered a data leak file associated with this domain. According to the hacker, this domain was allegedly hacked. If there are no other sources attached to this hack notice, then we don't have an official disclosure of a data incident, so this plug is only implied.