The security researchers have discovered a new vulnerability called CVE-2023-40680, which affects the popular WordPress plugin Yoast SEO developed by Team Yoast. This vulnerability is classified as "Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')" and allows an attacker to perform Stored XSS (Cross-site Scripting) attacks on the affected web applications. This issue impacts Yoast SEO versions from n/a through 21..

What is Stored XSS?
Stored XSS, also known as Persistent XSS, is a type of Cross-site Scripting vulnerability that occurs when an attacker injects a malicious script into a vulnerable web application, and this script is then stored on the server-side. When other users visit the affected web page, the malicious script is executed by their web browsers, allowing the attacker to steal sensitive information, manipulate website content, and perform various unauthorized actions.

Exploit Details

The vulnerability in Yoast SEO allows an attacker to inject malicious JavaScript code into specific parts of the affected web application by exploiting the improper neutralization of input during web page generation. This can lead to the execution of unauthorized scripts, modification of web page content, and potential theft of sensitive user information such as login credentials, personal details, and cookies.

- CVE Reference:
- National Vulnerability Database (NVD) Reference:
- Official Yoast SEO Plugin Reference:

Code Snippet Example

Let's say an attacker discovers this vulnerability in the affected Yoast SEO plugin. The attacker can inject malicious JavaScript code into a specific part of the web application by crafting a payload like this:

<script>alert('XSS Vulnerability Found')</script>

When this code is injected into a vulnerable web application, the server does not properly neutralize or sanitize the input before generating the web page. This will cause the injected script to be executed when the affected web page is opened by any user, potentially compromising their personal information or use of the website.

Possible Mitigation Techniques

1. To protect your website from this vulnerability, make sure to update the Yoast SEO plugin to the latest version (21.1 or higher). Team Yoast has released a patch addressing this issue in version 21.1.

2. Strictly enforce input validation on all user-provided data. By applying a whitelist approach, only allow specific types of input characters and properly validate and sanitize them before processing.

3. Implement Content Security Policies (CSP) to prevent stored XSS attacks by enforcing execution of scripts only from trusted sources.

4. Consider using anti-XSS libraries such as the OWASP (Open Web Application Security Project) Anti-XSS library to help defend against stored XSS vulnerabilities.


In conclusion, the CVE-2023-40680 vulnerability is a critical security issue that can have severe consequences if left unaddressed. To protect your website from this threat, update the Yoast SEO plugin to the latest version, and implement the aforementioned mitigation techniques. Stay informed and proactive about your website's security to ensure that you stay ahead of potential security threats.


Published on: 11/30/2023 13:15:07 UTC
Last modified on: 12/05/2023 19:17:20 UTC