An elevation of privilege vulnerability exists when Microsoft SharePoint Server does not properly sanitize a specially crafted web request to an affected SharePoint server. An authenticated attacker could exploit the vulnerability by sending a specially crafted URL to a user of an affected SharePoint server.
An attacker who successfully exploited the vulnerability could redirect users who are trying to access Silverlight content on an affected SharePoint server to malicious content if the targeted user does not already have Silverlight installed. This vulnerability requires that the user does not have Silverlight installed, clicks the specially crafted URL from the attacker, and clicks the link provided on SharePoint page to download Silverlight.
The security update addresses the vulnerability by helping to ensure that SharePoint Server properly sanitizes web requests.