Blizzard has been forced to issue a security warning to World of Warcraft players after a recent increase in "unauthorised World of Warcraft account-logins via [its] website and the World of Warcraft mobile armory app".
Explaining the security issue on Battle.net, Blizzard explained that it was "in the process of notifying any account holders who were not using an authenticator and whose account showed signs of unauthorized access (e.g., logging in from an unusual IP address).
"If you are among this group, you will receive an email describing how to reset your account."
Blizzard has also temporarily shut down access to the World of Warcraft auction house via the mobile app.
The developer adds that is has "no reason to believe that accounts currently using an authenticator are at risk".