AT&T is investigating a leak that put millions of customers’ data on the dark web

AT&T revealed Saturday that it is looking into an incident two weeks ago that resulted in millions of customers’ data being exposed on the dark web, a section of the Internet that can only be accessed with special software.

The company has reset the passcodes of the 7.6 million current users who were affected, and it is actively contacting them, as well as the 65.4 million former account holders whose data was also exposed.

“As of today, this incident has not had a material impact on AT&T’s operations,” the company stated in a press release issued Saturday.

AT&T’s preliminary investigation discovered that the disclosed data was dated 2019 or earlier and contained personal information such as names, home addresses, phone numbers, dates of birth, and Social Security numbers. The dataset does not include personal financial information or call history.

AT&T has recommended affected individuals to set up fraud alert accounts and watch their account activity and credit reports, as they will be notified via email. The company has yet to identify the source of the leak.

AT&T customers had an hours-long cellular outage in February, which the firm later said was caused by a system fault rather than a cyberattack. The company’s CEO, John Stankey, later apologized for the incident and issued customer credits to individuals affected.

CLARIFICATION: AT&T said it is looking into an issue two weeks ago that resulted in millions of customers’ data being published on the dark web. It’s unclear whether the system was breached.