Personal data belonging to 73 million current or former AT&T customers has been exposed online.
The leaked information includes addresses, social security numbers, and passcodes, and was discovered on the dark web, according to the US telecoms giant.
AT&T stated that while they have not found evidence indicating the data was stolen, they have enlisted cybersecurity experts to conduct an investigation.
As a precautionary measure, the company has reset customers’ passcodes and advised them to monitor their account activity and credit reports.
The compromised data appears to be from 2019 or earlier and affects 7.6 million current customers and 65.4 million former account holders. It includes details such as full names, email addresses, and dates of birth, although AT&T assured that financial information was not part of the leak.
In a statement, AT&T mentioned uncertainty regarding the source of the data, whether from their own systems or a third-party supplier.
Covering approximately 290 million people across the US with its wireless 5G network, AT&T is one of the largest mobile and internet service providers in the country.
Earlier this year, the company faced scrutiny after a significant outage left tens of thousands of phone users unable to use their devices for approximately 12 hours. Prosecutors in New York launched an investigation into the incident, prompting AT&T to issue apologies and offer affected users a $5 credit.