Mail in Apple Mac OS X before 10.7.5 does not properly handle embedded web plugins, which allows remote attackers to execute arbitrary plugin code via an e-mail message that triggers the loading of a third-party plugin.
https://exchange.xforce.ibmcloud.com/vulnerabilities/78751
http://support.apple.com/kb/HT5501
http://lists.apple.com/archives/security-announce/2012/Sep/msg00004.html