The phone numbers and personal data of over 553 million Facebook users have been published online for free by a user in a low-level hacking forum, according to Business Insider. At least 100 countries are included in this leak, with data from 32 million users in the U.S. and 11 millions users in the UK.

This breach includes phone numbers, Facebook IDs, full names, locations, birthdates, bios, and in some cases email addresses.

To Business Insider, Alon Gal, CTO of cybercrime intelligence firm Hudson Rock, who first discovered the leaked data on Saturday, said:

Insider reviewed a sample of the leaked data and verified several records by matching known Facebook users’ phone numbers with the IDs listed in the data set. We also verified records by testing email addresses from the data set in Facebook’s password reset feature, which can be used to partially reveal a user’s phone number.

All 533,000,000 Facebook records were just leaked for free.

This means that if you have a Facebook account, it is extremely likely the phone number used for the account was leaked.

I have yet to see Facebook acknowledging this absolute negligence of your data. https://t.co/ysGCPZm5U3 pic.twitter.com/nM0Fu4GDY8

— Alon Gal (Under the Breach) (@UnderTheBreach) April 3, 2021

It’s not the first time Facebook has its users’ data leaked online. In 2020, Mark Zuckerberg’s company was involved in a controversial situation regarding privacy issues and confirmed that thousands of developers had been able to access data from inactive users, which is unexpected behavior.

“A database of that size containing the private information such as phone numbers of a lot of Facebook’s users would certainly lead to bad actors taking advantage of the data to perform social engineering attacks [or] hacking attempts.”

Before that, there was the Cambridge Analytica controversy, in which the company not only got access to the data of anyone who gave permission to a third-party ‘personality quiz,’ but Facebook allowed the app some access to the data of their friends also.

The company has not addressed this new data leak yet, but it could be the worst leak Facebook’s ever been involved.

This morning, we reported that Apple’s CEO Tim Cook is being interviewed on Monday about the company’s new App Tracking Transparency policies change. Cook will also talk about Parlor and Facebook criticism over these tracking changes. The Apple’s CEO quote couldn’t fit more for the moment:

“Yeah, Kara, I’m not focused on Facebook. So I don’t know.”