Backup in Apple iOS before 8.4.1 allows attackers to bypass intended restrictions on filesystem access via a crafted app that creates a symlink.
https://support.apple.com/kb/HT205030
http://www.securitytracker.com/id/1033275
http://www.securityfocus.com/bid/76337
http://lists.apple.com/archives/security-announce/2015/Aug/msg00002.html