A security flaw in the Facebook API allows hackers to decrypt and scan user IDs. Nearly 1.44 billion Facebook users are at risk of identity theft. Threat actors can potentially steal all user information and sell them in the black market. Facebook should be able to solve the issue by limiting requests from a single user, and detecting patterns, before moving on to pre-encrypting all of its data. Facebook appears a bit careless, and according to the expert it is putting at risk user data.”]
Source: http://securityaffairs.co/wordpress/39293/hacking/facebook-api-identity-theft.html