An elevation of privilege vulnerability exists when the Windows Background Intelligent Transfer Service (BITS) IIS module improperly handles uploaded content. An attacker who successfully exploited this vulnerability could upload restricted file types to an IIS-hosted folder. To exploit this vulnerability, an attacker would require permissions to upload files via BITS. An attacker could then submit a specially crafted request to upload a file. The security update addresses the vulnerability by correcting how Windows BITS validates file names.