AT&T
View of AT&T communications company building in Mexico City on Dec. 3, 2018. OMAR TORRES/AFP/GETTY IMAGES

AT&T is conducting an investigation into a leak that has resulted in millions of customers' data being exposed on the dark web.

According to AT&T, the source of the data is still under investigation. It remains unknown whether the data originated from the company itself or from one of its vendors, reported Reuters.

The telecom giant stated that the leaked dataset appears to be from 2019 or earlier. It impacts approximately 7.6 million current AT&T account holders and 65.4 million former account holders.

The leaked dataset contains names, home addresses, phone numbers, Social Security numbers, and dates of birth.

"The company is communicating proactively with those impacted and will be offering credit monitoring at our expense where applicable," according to the statement as reported by Bloomberg.

AT&T stated that it currently lacks evidence of unauthorized access to its systems and that, as of Saturday, the leak has not had a material impact on its operations. However, the company did reset millions of customer account passwords following the leak.

Three years ago, rumors of an AT&T data leak began circulating after a hacker allegedly posted what they claimed were 70 million AT&T records to a forum in August 2021.

The company attributed the data breach to a third-party vendor that suffered a hacking incident in January, clarifying that its own system remained unaffected. Additionally, in February of this year, a massive outage left 70,000 users without a phone signal for several hours.

With about 87 million subscribers, AT&T is the third-largest U.S. retail wireless carrier, behind Verizon Communications and T-Mobile, according to data compiled by Bloomberg.