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 exists within the usage of execCommand("selectAll") and selection.clear which can cause a CSegment object to be freed. 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.