Hundreds of millions of phone numbers linked to Facebook accounts were found online.
The exposed server contained more than 419 million records in various databases for users from various geographic regions: 133 million records of Facebook users from the US, 18 million records of users from the UK, and more than 50 million records of users in Vietnam.
This particular server was not password protected, so anyone could access the huge database.
Each entry contained the Facebook user's unique ID and the phone number listed on the account. A user's Facebook ID is usually a long, unique, and public number associated with their account, which can be used very easily to clarify the username of an account.
However, the phone numbers have not been public for more than a year, as Facebook restricts access to users' phone numbers.
Some of the files also contained the user's name, gender and geographical location by country.
This is the latest data leak from Facebook after a series of incidents starting with the Cambridge Analytica, which exposed more than 80 million profiles.
Since then, the company has seen several high-profile breaches.
This latest incident exposed millions of users' phone numbers from their Facebook IDs alone, putting them at risk from spam calls and SIM swapping attacks.
This attack spoofs the target's mobile phone provider and changes their phone number. With the new phone number, the attacker can reset the password to any online account linked to that number.
Sanyam Jain, a security researcher and member of the GDI Foundation, found the database and contacted TechCrunch after failing to find the owner.
After a search of the data, Jain reported finding profiles with phone numbers of several celebrities.
The researcher reported that he removed the database from the internet on his own, since he could not find the owner.
