Many news sites are reporting a vulnerability (dubbed the Heartbleed bug) discovered in OpenSSL, an encryption technology used by a majority of websites and online services—including banks, email providers, and social media sites—to protect sensitive data as it’s transmitted from users to web services.
We want to emphasize that Battle.net’s encryption was not affected by this vulnerability. However, if you use the same password on Battle.net that you use elsewhere, your Battle.net account could be at risk if those sites were affected by this bug.
If the above situation applies to you, we recommend changing your Battle.net password to a new, unique password. As always, we recommend that you maintain separate login credentials for each online service you use. Using the same email or password across multiple services greatly increases the potential impact of any compromise.
More information about the Heartbleed vulnerability can be found at http://heartbleed.com, and you can find additional information on how to protect your Battle.net accounts at http://www.battle.net/security.