Use-after-free vulnerability in Microsoft Internet Explorer 9 and 10 allows remote attackers to execute arbitrary code via vectors involving crafted JavaScript code, CMarkup, and the onpropertychange attribute of a script element, as exploited in the wild in January and February 2014.
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2014/ms14-012
http://technet.microsoft.com/security/advisory/2934088
http://twitter.com/nanoc0re/statuses/434251658344673281
http://www.exploit-db.com/exploits/32851