The iCloud subsystem in Apple iOS before 7.1 allows physically proximate attackers to bypass an intended password requirement, and turn off the Find My iPhone service or complete a Delete Account action and then associate this service with a different Apple ID account, by entering an arbitrary iCloud Account Password value and a blank iCloud Account Description value.
http://support.apple.com/kb/HT6162
http://news.softpedia.com/news/Major-iOS-7-Security-Flaw-Discovered-Video-425011.shtml