In a major security breach, personal information belonging to millions of AT&T customers has been leaked online, including sensitive details such as Social Security numbers (SSNs), passcodes, and contact information, the telecommunications giant announced on Saturday. The leaked data, discovered on the "dark web," reportedly includes information on approximately 7.6 million current AT&T account holders and 65.4 million former users, affecting a staggering total of around 73 million accounts.

AT&T revealed that it remains uncertain whether the data breach originated from the company itself or one of its vendors. However, it affirmed that the compromised data appears to be from 2019 or earlier and does not contain personal financial information or call history.

The company has taken immediate action by resetting passcodes for the affected 7.6 million current account holders. Notifications about the breach are being sent out, and AT&T is conducting a thorough investigation into the incident.

Alongside passcodes and SSNs, other potentially exposed information includes email and mailing addresses, phone numbers, and birth dates. The breach first came to light on a hacking forum almost two weeks ago. It remains unclear if this latest leak is related to a previous breach in 2021 that received widespread attention but was not acknowledged by AT&T.

The 2021 breach involved a hacker who claimed to possess data of 70 million AT&T customers, including their names, addresses, phone numbers, SSNs, and dates of birth. The hacker reportedly attempted to sell the stolen information on a hacking forum for thousands of dollars.

Cybersecurity expert Troy Hunt, the creator of Have I Been Pwned?, a website that alerts users to data breaches, warned that AT&T may face class action lawsuits if it is determined that they were aware of the breach but failed to notify affected customers in a timely manner. In fact, Hunt confirmed that at least 153,000 of his customers were impacted by this breach.

This unfortunate incident adds to AT&T's recent challenges, as it faced a mobile phone service outage in February that affected thousands of users. The company attributed the outage to a technical coding error rather than a malicious attack, though it impacted AT&T more severely than other networks.

As AT&T grapples with this massive data breach, the focus is now on mitigating the fallout and strengthening cybersecurity measures to prevent future incidents. Customers are urged to remain vigilant and take necessary precautions to protect their personal information.