Epic Games announced last night that its forums were compromised, which "may have resulted in unauthorized access to your username, email address, password, and the date of birth you provided at registration."
Epic said in a statement that the UDK, Infinity Blade, Gears of War, Bulletstorm, and older Unreal Tournament forums were affected by the hack, but that forums on separate sites for Unreal Engine 4, Fortnite, and the latest Unreal Tournament were not touched. The forums have been taken offline while Epic works with a computer security firm to determine the nature and extent of the hack, and all passwords will be reset when they come back.
"It is possible that any information stored or sent by you using the forums may have been accessed," the statement says. "Since this is a public forum, we do not collect or maintain financial information, but we advise you to be alert for suspicious email such as phishing attempts."
If you use the same password for internet forums as you do for, say, your online banking (which, for the record, you definitely shouldn't), you'll want to get on with changing them as soon as you can.