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 the way the library implements the .sort function for an array. The library will trust the implementation of a particular method which when executed can be used to manipulate elements out from underneath it. This can lead to code execution under the context of the application.
Patch Availability:
Apple has issued an update to correct this vulnerability. More details can be found at: http://support.apple.com/kb/HT4554