This vulnerability allows remote attackers to execute arbitrary code on vulnerable installations of Microsoft Internet Explorer. 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 is due to the way mshtml handles a CDOMTextNode. When using a selection to get focusNode, the process can be made to create a CDOMTextNode and later delete this CDOMTextNode resulting in a dangling pointer. The process can be later forced to reuse this pointer resulting in a use-after-free condition. An attacker can leverage this situation to execute code under the context of the user running the browser.