Apple iTunes before 11.0.3 does not properly verify X.509 certificates, which allows man-in-the-middle attackers to spoof HTTPS servers via an arbitrary valid certificate.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A17605
http://support.apple.com/kb/HT5766
http://lists.apple.com/archives/security-announce/2013/May/msg00000.html