This security update KB960803 for Windows Vista 64-bit/2008 64-bit resolves one publicly disclosed vulnerability and two privately reported vulnerabilities in Microsoft Windows HTTP Services (WinHTTP). The most severe vulnerability could allow remote code execution. 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.