Nearly 9 million AT&T customers had some of their data compromised following a hack into a marketing vendor's systems, reports BleepingComputer. AT&T has announced that individuals impacted by the breach, which has exposed their Customer Proprietary Network Information including their first names, email addresses, wireless account numbers, and wireless phone numbers have already been notified. "A small percentage of impacted customers also had exposure of rate plan name, past due amount, monthly payment amount, various monthly charges, and/or minutes used. The information was several years old," said AT&T. However, no Social Security numbers, credit card details, account passwords, and other sensitive personal data were involved in the incident. AT&T also emphasized that the intrusion did not impact its systems and that federal law enforcement has already been informed regarding the incident. "Our report to law enforcement does not contain specific information about your account, only that the unauthorized access occurred," added AT&T.