An elevation of privilege vulnerability exists when Microsoft SharePoint Server and Skype for Business Server improperly handle OAuth token validation. An attacker who successfully exploited the vulnerability could bypass authentication and achieve improper access. To exploit this vulnerability, an attacker would need to modify the token. The update addresses the vulnerability by modifying how Microsoft SharePoint Server and Skype for Business Server validate tokens.

An elevation of privilege vulnerability exists when Microsoft SharePoint Server and Skype for Business Server improperly handle OAuth token validation, aka 'Microsoft Office Elevation of Privilege Vulnerability'.