A buffer overrun vulnerability affecting many Microsoft OS and applications (including Office) has been patched. The problem exists in the processing of JPEG image formats that could allow remote code execution on an affected system. Good news is, if you are running SP2 you should be safe, otherwise we recommend, patch your system inmediately.
If a user is logged on with administrator privileges, an attacker who successfully exploited this vulnerability could take complete control of an affected system, including installing programs; viewing, changing, or deleting data; or creating new accounts with full privileges. Users whose accounts are configured to have fewer privileges on the system would be at less risk than users who operate with administrative privileges.