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Bug in Facebook may have exposed your phone number to marketers

It’s a well-known fact that having a Facebook account isn’t great for your privacy. If you aren’t careful, you could post the wrong thing to the world and get in trouble at work, school, with family or even the law.

If that wasn’t bad enough, hackers and identity thieves are always trying to get a peek at your account to pick up tidbits they can use against you. The social media giant has tried to make things better with things like its Security Checkup.

Unfortunately, a bug was recently discovered that could have exposed your phone number to the wild.

Has Facebook mistakenly given out your phone number?

Facebook has settings that allow you to choose who can see certain information. For example, you decide who can see your posts.

Choose between Public, Friends, Friends except (block certain friends), Specific friends, or Only me. You have the same choices when it comes to personal information like your relationship status, work history, phone number, etc.

It turns out that until recently, a bug in Facebook’s own system was allowing phone numbers to be seen by marketing agencies without permission. Facebook’s self-service ad-targeting tools were the culprit.

A team of researchers discovered the flaw in May 2017. It took Facebook until December 22, 2017, to fix it.

The researchers found that the advertising tool could be exploited to show a user’s phone number by way of their email address. Marketers could also gather users’ phone numbers if they visited a certain webpage.

The tool in question is called Custom Audiences. Advertisers can use it to upload anonymized customer data to pinpoint users who fit their target.

Facebook can then let advertisers know how many of its users will see an ad that is targeted to specific lists. It also tells the advertisers the portion of the list that overlaps other lists. This is where the bug was found. The overlap list could have been manipulated to show user data.

It took Facebook seven months to fix the bug by changing its tool to no longer show audience sizes when user data is used to create new marketing lists.

The scary thing about this flaw is how easy it is to become an advertiser on Facebook. There are advertising plans for as little as $1 per day, which is a cost-effective way for small-time criminals to get their hands on sensitive data.

Even though Facebook has fixed this bug, you still should be careful with what you post on the site. Also, make sure that your privacy settings are set to your liking. Read the following article for more helpful Facebook privacy tips.


Facebook knows a lot about you and the companies they work with know a lot about you. There is great news, though, when it comes to your privacy. Facebook has made it easy to manage your privacy settings.

Click here for a simple trick to protect your privacy. App background

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