Is Facebook secretly sharing your phone number?

An irate Twitter user has recently revealed that giving Facebook your phone number makes it publicly searchable to everyone.

Like many other sites, Facebook prompts you to add a mobile number – which not only helps you find friends, but is also used to apply two-factor authentication (2FA). This safety measure adds an extra layer of security to your online accounts by texting an access code to your phone that’s used to confirm your identity in addition to a password.

In an alarming thread, @jeremyburge revealed that “for years Facebook claimed that adding a number for 2FA was only for security. Now, it can be searched and there’s no way to disable it”.

To make matters worse, the social-media site is sharing that information with its other enterprises – Burge claims that Facebook 2FA numbers are also shared with Instagram, which prompts you with “Is this your number?” once you add it to Facebook.

This isn’t the first time that mobile numbers have been misused by Facebook. Last year, tech website Gizmodo reported that the social network used phone numbers to sell targeted ads.

According to Facebook’s Help guide, users can control who can see personal information such as phone numbers, but they may still be visible “when someone uploads your contact info to Facebook from their mobile phone”.