Zero-Day Advisory

Fortinet Discovers WordPress (Core) Cross-Site Scripting Vulnerability


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

WordPress is one of the world's most popular content management system (CMS). WordPress is by far the most popular CMS with 60.4% of the market share. This means WordPress is used by 33.5% of all the websites online.

An XSS vulnerability has been discovered in WordPress 5.2.2 and earlier versions. The vulnerability is caused by inadequate input filtering of HTML encoded characters which can lead to XSS attacks in the Shortcode function.


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

Released Dec 24, 2018

Users should apply the solution provided by WordPress.


Fortinet reported the vulnerability to WordPress on December 11, 2018.

WordPress confirmed the vulnerability on December 24, 2018.

WordPress patched the vulnerability on September 5, 2019.


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.