A spoofing vulnerability exists when a Skype for Business Server does not properly sanitize a specially crafted request. An authenticated attacker could exploit the vulnerability by sending a specially crafted request to an affected server. The attacker who successfully exploited this vulnerability could then perform cross-site scripting attacks on affected systems and run scripts in the security context of the current user. For the vulnerability to be exploited, a user must click a specially crafted URL that takes the user to a targeted Skype for Business site. In an email attack scenario, an attacker could exploit the vulnerability by sending an email message containing the specially crafted URL to the user of the targeted Skype for Business site and convincing the user to click the specially crafted URL.