The UIKit View component in Apple iOS before 8.3 displays unblurred application snapshots in the Task Switcher, which makes it easier for physically proximate attackers to obtain sensitive information by reading the device screen.
https://support.apple.com/HT204661
http://www.securitytracker.com/id/1032050
http://www.securityfocus.com/bid/73978
http://lists.apple.com/archives/security-announce/2015/Apr/msg00002.html