It seems it's quite hard to keep private data actually private, even for the almighty Facebook. A database with telephone numbers of possibly hundreds of millions of Facebook users was spotted online, totally unprotected. It is unknown who uploaded the database and why. 

The database contained 419 million entries, according to Facebook, half of them are duplicates, meaning that it would be the data of several hundred million users. The database showed unique IDs of Facebook users, linked to their telephone numbers and in some cases also with name, gender and country. Facebook IDs are unique and can be traced back to accounts. According to a report from TechCrunch, the dataset had included 133 million records from U.S.-based Facebook users, 18 million from the U.K., and over 50 million from Vietnam.

The latest security incident is seen by cybersecurity experts as an alarming issue that can put affected users at risk of receiving spam calls and SIM-swapping attacks. “With someone else’s phone number, an attacker can force-reset the password on any internet account associated with that number,” TechCrunch explained.

In March 2018, Facebook revealed that Cambridge Analytica, a firm that worked for Donald Trump’s 2016 presidential campaign, had obtained the personal data of up to 71 million Americans. This had led to Facebook having to pay a whopping $5 billion to settle the charge.

In the same year, millions of Facebook and Instagram users’ details had been exposed due to a data breach. A few months later, the social media giant announced that a data breach had affected the accounts of about 29 million of its users.

The database is now offline.

Facebook database holding 419 million user entries was posted online