Zero-Day Advisory

Fortinet Discovers Joomla! Specific HTML Attribute Cross-Site Scripting Vulnerability


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

Joomla! is one of the world's most popular content management system (CMS). It enables users to build Web sites and powerful online applications. More than 3 percent of Web sites are running Joomla! and it accounts for more than 9 percent of CMS market share.

A XSS vulnerability has been discovered in Joomla! 3.6.5 and earlier versions. It is caused by inadequate filtering of specific HTML attributes which leads to XSS vulnerabilities in various components.


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

Released Feb 27, 2017

FortiWeb can protect this specific vulnerability since the signature package 0.00178.

Users should apply the solution provided by Joomla!.

Additional Information

Fortinet reported the vulnerability to Joomla! on Feb. 22, 2017.

Joomla! confirmed the vulnerability on Feb. 24, 2017.

Joomla! patched the vulnerability on Apr. 25, 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.