Epic Games' forums have been pulled offline following a hack, the company has confirmed.
In an email to forum members, the game maker said its gaming communities had been "compromised by a hacker," leading to the theft of registration data, such as usernames, email addresses, and passwords.
The site's gaming communities -- UDK, Infinity Blade, Gears of War, Bulletstorm, and prior Unreal Tournament games -- are primarily affected.
The company said it is working with a security firm to determine the root of the intrusion.
However, it's thought that the unpatched forum software may be to blame, with the communities running an outdated version of VBulletin. Two years ago, the forum-making company was hit by a hack of its own, making off with hundreds of thousands of VBulletin usernames and passwords.
Users will be prompted to reset their forum password when they next login, the company said.