Hackers may have stolen the Social Security numbers of all Americans. Here's what to know.

A new lawsuit is claiming hackers have gained access to the personal information of "billions of individuals," including their Social Security numbers, current and past addresses and the names of siblings and parents — personal data that could allow fraudsters to infiltrate financial accounts or take out loans in their names. 

The allegation arose in a lawsuit filed earlier this month by Christopher Hofmann, a California resident who claims his identity theft protection service alerted him that his personal information had been leaked to the dark web by the "nationalpublicdata.com" breach. The lawsuit was earlier reported by Bloomberg Law.

The breach allegedly occurred around April 2024, with a hacker group called USDoD exfiltrating the unencrypted personal information of billions of individuals from a company called National Public Data (NPD), a background check company, according to the lawsuit. Earlier this month, a hacker leaked a version of the stolen NPD data for free on a hacking forum, tech site Bleeping Computer reported.