Zero-Day Advisory

Fortinet Discovers Microsoft SharePoint Cross-Site Scripting Vulnerability


Fortinet's FortiGuard Labs has discovered a Cross-Site Scripting (XSS) vulnerability in Microsoft SharePoint.

SharePoint is a web application platform in the Microsoft Office server suite. SharePoint combines various functions. SharePoint servers have traditionally been deployed for internal use in mid-size businesses and large departments alongside Microsoft Exchange, Skype for Business, and Office Web Application Server.

An XSS vulnerability has been discovered in SharePoint 2016. The vulnerability is caused due to insufficiently sanitizing user-supplied input in a number of input fields like notes, keywords and comments. It allows remote attackers to launch XSS attacks. Attackers can exploit this vulnerability to inject malicious JavaScript code to potentially issue SharePoint commands in the context of another authenticated user.


FortiGuard Labs released the following FortiGate IPS signature which covers this specific vulnerability:

Released Jul 21, 2016

Users should apply the solution provided by Microsoft.


Fortinet reported the vulnerability to Microsoft on June 08, 2016.

Microsoft confirmed the vulnerability on June 21, 2016.

Microsoft patched the vulnerability on January 10, 2017.


This vulnerability was discovered by Zhouyuan Yang of Fortinet's FortiGuard Labs.

IPS Subscription

Fortinet customers who subscribe to Fortinet's intrusion prevention (IPS) service should be protected against this vulnerability with the appropriate configuration parameters in place. Fortinet's IPS service is one component of FortiGuard Subscription Services, which also offer comprehensive solutions such as antivirus, Web content filtering and antispam capabilities. These services enable protection against threats on both application and network layers. FortiGuard Services are continuously updated by FortiGuard Labs, which enables Fortinet to deliver a combination of multi-layered security intelligence and true zero-day protection from new and emerging threats. These updates are delivered to all FortiGate, FortiMail and FortiClient products. Fortinet strictly follows responsible disclosure guidelines to ensure optimum protection during a threat's lifecycle.