Former and current AT&T customers, numbering 73 million, are facing the leak of their personal data, as reported by the BBC.

The US telecommunications giant said the leak involved information such as addresses, social security numbers and passwords that had been published on the dark web.

AT&T said it had no evidence that data had been stolen, but brought in cybersecurity experts to investigate.

The company said it has changed customers’ passwords and urged them to “remain vigilant by monitoring account activity and credit reports.”

The leaked data appears to date back to 2019 or earlier and relates to 7.6 million current customers and 65.4 former customers.

Included in the leaked data are full names, email addresses and dates of birth, although AT&T said no financial information was disclosed.

The company also said it was unclear whether the data came from its own systems or from a third-party vendor.

AT&T’s 5G wireless network covers about 290 million people in the US, and the company is one of the country’s largest mobile and internet service providers.

In February, a major outage affected tens of thousands of phone users. AT&T responded with an apology and a $5 credit for those affected.

Prosecutors in New York have launched an investigation into the episode, which left users without phone and internet for about 12 hours.