If you use the RealPlayer on Internet Explorer, watch out. Researcher Elazar Broad has posted to the Full Disclosure mailing list a so-called heap overflow vulnerability that makes it possible for an attacker to modify heap blocks after they are freed and overwrite certain registers. This could allow code execution on a compromised machine. The vulnerability affects all versions of RealPlayer running under Internet Explorer.
Exploit code for this flaw has not yet been made public.
Without a patch from RealPlayer, security experts recommend disabling the killbit for the following ActiveX ClassIDs: