According to this EA forum thread, some Origin users are claiming that their accounts are being hijacked. Customers claiming that their accounts are being hijacked are receiving emails from EA informing them that their email address and password have been "successfully updated" even though they themselves have not attempted to update any of their account settings. The original account owners found that they could not access their accounts because the account thieves are also editing information that is typically used to verify ownership, such as the user's birth date.
EA's Origin support department seem to be dealing with account theft on a case-by-case basis. At this point it is unclear what exactly is going on with the service and these particular customers. When we have more information we'll update this story. EA has not issued any statements on the matter as of this writing.