A data leak has impacted 73 million current and former AT&T users, leading to a reset of passcodes. The leaked information includes full names, email addresses, social security numbers, and more. The data set, which was originally from 2019 or earlier, has now appeared both on the dark web and open web. Security researcher Troy Hunt emphasized that the term 'dark web' is misleading in this case. Additionally, a file with 73,481,539 lines of data containing 49,102,176 unique email addresses has been added to the 'Have I Been Pwned' database. AT&T has acknowledged the leak, stating that it may have originated from AT&T or one of its vendors. The company is proactively reaching out to those impacted and offering credit monitoring. This incident follows a 2021 incident where a hacker attempted to sell the same data set for $1 million, to which AT&T denied it originated from their systems. The situation is being assessed, and AT&T continues to communicate with those affected.