This update resolves several newly-discovered, publicly and privately reported vulnerabilities. Each vulnerability is documented in its own “Vulnerability Details” section of this bulletin.
If a user is logged on with administrative user rights, an attacker who successfully exploited the most severe of these vulnerabilities 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.
We recommend that customers apply the update immediately.
Details:
http://www.microsoft.com/technet/sec.../MS06-013.mspx