Hundreds of millions of phone numbers linked to Facebook accounts have been found online. The exposed server contained more than 419 million records over several databases on users across geographies, including 133 million records on U.S.-based Facebook users, 18 million records of users in the U.K., and another with more than 50 million records on users in Vietnam. But because the server wasn’t protected with a password, anyone could find and access the database. Each record contained a user’s unique Facebook ID and the phone number listed on the account. A user’s Facebook ID is typically a long, unique and public number associated with their account, which can be easily used to discern an account’s username.
But phone numbers have not been public in more than a year since Facebook restricted access to users’ phone numbers. TechCrunch verified a number of records in the database by matching a known Facebook user’s phone number against their listed Facebook ID. We also checked other records by matching phone numbers against Facebook’s own password reset feature, which can be used to partially reveal a user’s phone number linked to their account.Source: TechCrunch
Some of the records also had the user’s name, gender and location by country.