Microsoft Security Advisory (951306)
Vulnerability in Windows Could Allow Elevation of Privilege
Published: April 17, 2008
Microsoft is investigating new public reports of a vulnerability which could allow elevation of privilege from authenticated user to LocalSystem, affecting Windows XP Professional Service Pack 2 and all supported versions and editions of Windows Server 2003, Windows Vista, and Windows Server 2008.
Source: TechNet
See also: MSRC Blog