Facebook Bug Could Have Revealed User Phone Numbers to Advertisers

Facebook has announced that a system bug may have revealed users’ personal phone numbers to advertisers.

WIRED reports that a bug in Facebook’s ad-targeting tools allowed advertisers to gain Facebook users’ phone numbers from their email address and even gave advertisers access to the phone numbers of users that visited a particular web page. The issue was reported by a group of researchers from the U.S., France, and Germany at the end of May. Facebook paid out a “bug bounty” of $5000 to the researchers at the time and implemented a fix for the bug on December 22.

The bug represents a huge breach of Facebook’s data-use policy which specifically states, “We do not share information that personally identifies you … with advertising, measurement or analytics partners unless you give us permission.” Facebook has stated that to their knowledge, no one has used the exploit to gain access to user data due to the level of skill required to trigger the bug, but according to Neil Gong, a professor at Iowa State who works on social-network privacy, this issue represents a larger problem with Facebook’s business model.

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