Zero-Day Advisory

Fortinet Discovers Joomla! Cross-Site Scripting Vulnerability


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

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! 3.8.7 and earlier versions. It is caused by inadequate input filtering of line feed character which leads to XSS vulnerabilities in various components.


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

Released Mar 27, 2018

Users should apply the solution provided by Joomla!.


Fortinet reported the vulnerability to Joomla! on March 26, 2018.

Joomla! confirmed the vulnerability on March 27, 2018.

Joomla! patched the vulnerability  on May 22, 2018.


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.