Microsoft is aware of limited, targeted attacks that attempt to
exploit a vulnarability in Internet Explorer.
The vulnerability is a remote code execution vulnerability. The
vulnerability exists in the way that Internet Explorer accesses an object in
memory that has been deleted or has not been properly allocated. The
vulnerability may corrupt memory in a way that could allow an attacker to
execute arbitrary code in the context of the current user within Internet
Explorer. An attacker could host a specially crafted website that is designed
to exploit this vulnerability through Internet Explorer and then convince a user
to view the website.
It gave limited information on the bug, but admitted "an
attacker who successfully exploited this vulnerability could take complete
control of an affected system. An attacker could then install programs; view,
change, or delete data; or create new accounts with full user rights."