http://www.theverge.com/2013/2/14/3987830/ios-6-1-security-flaw-lets-anyone-make-calls-from-your-iphone
A security flaw in Apple's iOS 6.1 lets anyone bypass your iPhone password lock and access your phone app, view or modify contacts, check your voicemail, and look through your photos (by attempting to add a photo to a contact).
Something very similar happened with iOS 4.2 (see the article for a reference link).
The article also includes video footage of the flaw being taken advantage of.
