The Audio Drivers subsystem in Apple iOS before 8.3 and Apple TV before 7.2 does not properly validate IOKit object metadata, which allows attackers to execute arbitrary code in a privileged context via a crafted app.
http://lists.apple.com/archives/security-announce/2015/Apr/msg00002.html
http://lists.apple.com/archives/security-announce/2015/Apr/msg00003.html
https://support.apple.com/HT204661