Zero-Day Advisory

Fortinet Discovers Cisco Web Security Appliance Cross-Site Scripting Vulnerability


Fortinet's FortiGuard Labs has discovered a Cross-Site Scripting (XSS) vulnerability in Cisco Web Security Appliance.

Cisco Web Security Appliance (WSA) is an all-on-a-single platform. It can provide malware protection, application visibility and control, acceptable use policy controls, insightful reporting and secure mobility.

A XSS vulnerability has been discovered in Cisco WSA. It is caused by insufficient input validation of user-supplied value. An attacker could exploit this vulnerability by inputting malicious script code in vulnerable fields as a least-privileged user. The administrator user could be attacked by accessing the webpage storing the malicious script code. Successful exploit could allow the attacker to execute arbitrary script code in the context of the affected site or allow the attacker to access sensitive browser-based information.


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

Released Mar 15, 2017

Users should apply the solution provided by Cisco.

Additional Information

Fortinet reported the vulnerability to Cisco on July 8, 2016.

Cisco patched the vulnerability on August 10, 2017.


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.