AT&T Vendor Data Breach Exposed 9 Million Customer Accounts

AT&T customer data was exposed in January through a third-party vendor that had been hacked, the carrier confirmed, affecting around nine million customer accounts. This included basic personal information but no financial data or Social Security numbers.

The data that AT&T had provided to the marketing vendor which had been exposed was "mostly related to device upgrade eligibility," according to a statement from AT&T. It included basic personal information like customer names, account numbers, phone numbers and email addresses, as well as the number of lines on the account, devices used and installment agreement information.

The exposed data didn't include Social Security numbers, credit card information, account passwords or "other sensitive information," the AT&T statement said, and the carrier noted that the data set was several years old.

AT&T said that its own systems were not breached and that it was notifying customers who had been affected.