Apple iOS before 9.2, OS X before 10.11.2, and tvOS before 9.1 improperly validate keychain item ACLs, which allows attackers to obtain access to keychain items via a crafted app.
https://support.apple.com/HT205640
https://support.apple.com/HT205637
https://support.apple.com/HT205635
http://www.securitytracker.com/id/1034344
http://lists.apple.com/archives/security-announce/2015/Dec/msg00005.html
http://lists.apple.com/archives/security-announce/2015/Dec/msg00001.html
http://lists.apple.com/archives/security-announce/2015/Dec/msg00000.html