Apple Safari before 5.1.1 on Mac OS X does not enforce an intended policy for file: URLs, which allows remote attackers to execute arbitrary code via a crafted web site.
https://exchange.xforce.ibmcloud.com/vulnerabilities/70567
http://www.securityfocus.com/bid/50162
http://support.apple.com/kb/HT5000
http://lists.apple.com/archives/Security-announce/2011//Oct/msg00004.html