The security flaw, discovered by TechCrunch, relates to a feature on Facebook that allows users to preview their own privacy settings. Describing the problem, TechCrunch’s Steve O’Hear wrote: “There is a major security flaw in the social networking site that, with just a few mouse clicks, enables any user to view the live chats of their ‘friends’.
Full story: Facebook takes down chat after security flaw is exposed – Telegraph