kextd in Kext Management in Apple iOS before 7 does not properly verify authorization for IPC messages, which allows local users to (1) load or (2) unload kernel extensions via a crafted message.
http://lists.apple.com/archives/security-announce/2013/Oct/msg00004.html
http://lists.apple.com/archives/security-announce/2013/Sep/msg00006.html
http://secunia.com/advisories/54886