Hackers have broken into Blizzard Entertainment’s Battle.net service. They’ve stolen account details including email addresses, phone numbers, and encrypted passwords. The affected regions are China, North America, Latin America, Australia, New Zealand and Southeast Asia.
User’s passwords are safe at the moment but there’s no way to know how long it could take to crack them. It could be hours or years, it really depends how well they were encrypted.
If you have a Blizzard Battle.net account you should change your password now. And if you’re reused the password on other websites you should change those as well.