A hacker group gained access and exposed Americans’ data, including their social security numbers.

According to a complaint filed in the US District Court for the Southern District of Florida, the cybercriminals group, USDoD, published the data of 2.9 billion people.

The database was listed for sale at $3.5 million.

If confirmed, the breach could be among the largest ever, rivaling the 2013 Yahoo! hack that affected 3 billion users.

Christopher Hofmann, the plaintiff in the complaint, was notified in July that his data had been exposed. He accuses National Public Data (NPD) of failing to “properly secure and safeguard the personally identifiable information that it collected and maintained as part of its regular business practices.”

Hofmann is seeking monetary relief and greater security measures for private data.

A news release from Schubert Jonckheer & Kolbe LLP explains that the cybercriminal group seized the data in April 2024.

“Because individuals did not affirmatively provide their private information to NPD, individuals may not even know that they have been affected,” the release says. “To date, NPD has not confirmed the breach or what information may have been stolen.”