Zero-Day Advisory

Fortinet Discovers Microsoft Windows Webservices Library Denial of Service Vulnerability


Fortinet's FortiGuard Labs has discovered a Denial of Service vulnerability in Microsoft Windows Webservices Library.

Microsoft Windows is a group of graphical operating system families, all of which are developed and sold by Microsoft.

A Denial of Service vulnerability exists when Windows improperly handles objects in memory. An attacker who successfully exploited the vulnerability could cause a target Windows system to stop responding.


Users should apply the solution provided by Microsoft.

Additional Information

Following Windows versions are affected:

Windows 10

Windows 7

Windows 8.1

Windows RT 8.1

Windows Server 2008

Windows Server 2012

Windows Server 2016

Windows Server


Fortinet reported the vulnerability to Microsoft on January 5, 2018.

Microsoft confirmed the vulnerability on March 30, 2018.

Microsoft patched the vulnerability on June 12, 2018.


This vulnerability was discovered by Honggang Ren 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.