The popular Newsletter plugin for WordPress has been found to have a critical Stored Cross-Site Scripting (XSS) vulnerability. The vulnerability, tracked as CVE-2023-4772, affects the plugin version 7.8.9 and earlier. This issue poses a significant risk to WordPress websites using the Newsletter plugin. In this post, we will explain the vulnerability, how it can be exploited, and what you can do to protect your site. We will also provide links to original references for further information.

Description of Vulnerability

CVE-2023-4772 affects the 'newsletter_form' shortcode within the WordPress Newsletter plugin. Authenticated attackers with contributor-level permissions and higher can exploit this vulnerability by injecting arbitrary web scripts into affected pages.

The problem lies in insufficient input sanitization and output escaping on user-supplied attributes. When a user accesses an injected page, the attacker's malicious script will execute. Depending on the attacker's intent, this could lead to unwanted behavior ranging from simple nuisances to more severe security breaches.

For instance, attackers could steal sensitive information, redirect users to malicious websites, or even take control of the site itself.

Here's an example of how the vulnerability may be exploited by an attacker

[newsletter_form form="1" <img src=x onerror=alert('XSS') />]

In this example, the attacker injects an 'onerror' event that triggers an alert message with the text "XSS" into the 'newsletter_form' shortcode. When users view the page, the alert message will appear, indicating that the attacker's script has executed successfully.

Original References

Details about this vulnerability, including the affected versions, proof of concept, and remediation, are available from these trustworthy sources:

- The official CVE entry: CVE-2023-4772
- The plugin's developers have acknowledged the issue: Newsletter Plugin Security Advisory
- Additional technical details: Stored XSS Vulnerability in WordPress Newsletter Plugin

Exploit Details

Authenticated attackers with contributor-level permissions or higher can exploit this vulnerability by creating a new post or editing an existing one. They would then inject the malicious script into the 'newsletter_form' shortcode as shown in the code snippet above. Upon visiting the affected pages, the malicious script will execute for every user accessing the page.

How to Protect Your Site

To secure your WordPress website against this vulnerability, it is crucial to update the Newsletter plugin to version 7.9. or later to obtain the patch that addresses this issue.


CVE-2023-4772 presents a critical security risk for WordPress websites using the Newsletter plugin. It is vital to update your plugin to the latest version and continually monitor for updates to guarantee your site's safety. Always be diligent about your site's security and stay informed on new vulnerabilities and their corresponding fixes.


Published on: 09/07/2023 02:15:00 UTC
Last modified on: 09/11/2023 18:17:00 UTC