Yahoo announced yesterday that some Yahoo Mail account addresses and passwords were being used in a coordinated attempt to gain access to those accounts. The source of the account information remains unclear, but Yahoo claims that it was not obtained from Yahoo’s services directly.

Yahoo is resetting the passwords of affected accounts and informing the associated account holders.

Since it’s difficult to know, at this point, the full extent of this problem, anyone with a Yahoo Mail account is advised to immediately change its password.