User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file. The specific flaw exists within Webkit's support of character sets. If the IBM1147 character set is applied to a particular element and that element has a text transformation applied to it, the application will attempt to access an object that doesn't exist in order to perform the transformation. Successful exploitation will lead to code execution under the context of the web-browser.
Patch Availability:
Apple has issued an update to correct this vulnerability. More details can be found at: http://support.apple.com/kb/HT4196
