If a user is logged on with administrative user rights (which is all of us, right?), 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. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.
I normally don’t get hit with exploits, but this one hit me hard — so much so that after five hours of painful malware removal, registry key restoration, and many declarations of “Yes dear, it should only be another minute or two” I finally gave in and did a system restore.
Thank goodness for regular data backups! Needless to say, I’m now patched and protected (even moreso than before), and doing backups even more regularly.