CVE-2024-39647 in Message Filter for Contact Form 7 Plugin
Summary
by MITRE • 08/02/2024
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in Kofi Mokome Message Filter for Contact Form 7 cf7-message-filter.This issue affects Message Filter for Contact Form 7: from n/a through <= 1.6.1.1.
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Analysis
by VulDB Data Team • 04/02/2026
The CVE-2024-39647 vulnerability represents a critical cross-site scripting flaw in the Kofi Mokome Message Filter for Contact Form 7 plugin, specifically impacting versions through 1.6.1.1. This vulnerability falls under the CWE-79 category of Cross-Site Scripting, which is one of the most prevalent and dangerous web application security flaws. The issue occurs during the web page generation process when user input is improperly handled, creating an avenue for malicious actors to inject harmful scripts into web pages viewed by other users. The vulnerability is particularly concerning because it affects a widely used WordPress plugin that processes contact form submissions and generates messages, making it a prime target for attackers seeking to exploit user trust and access sensitive information.
The technical flaw stems from inadequate input sanitization within the message filtering mechanism of the Contact Form 7 plugin. When users submit contact forms containing malicious script code, the plugin fails to properly neutralize or escape this input before it is rendered in subsequent web pages. This allows attackers to inject malicious JavaScript code that executes in the context of other users' browsers when they view the filtered messages. The vulnerability is classified as a reflected XSS attack vector because the malicious code is reflected back to users through the plugin's message generation process. Attackers can craft specially formatted contact form submissions that, when processed by the vulnerable plugin, will execute arbitrary scripts in the browsers of other users who view the resulting messages.
The operational impact of this vulnerability is significant and multifaceted across multiple threat vectors. Attackers can leverage this weakness to steal user session cookies, enabling session hijacking and unauthorized access to user accounts. The vulnerability also allows for defacement of web pages, where malicious actors can modify content displayed to users in real-time. Additionally, the vulnerability can be exploited to redirect users to malicious websites, deliver malware payloads, or perform actions on behalf of users without their knowledge. Given that Contact Form 7 is one of the most popular WordPress contact form plugins, the potential attack surface is extensive, affecting countless websites that rely on this plugin for user communication. The vulnerability's persistence in versions up to 1.6.1.1 indicates a prolonged exposure window, increasing the likelihood of successful exploitation across various web applications.
Mitigation strategies for CVE-2024-39647 should prioritize immediate plugin updates to versions that address the XSS vulnerability, as recommended by the plugin developer and security advisories. Organizations should implement comprehensive input validation and output encoding mechanisms at multiple layers of their web applications to prevent similar issues in the future. The implementation of Content Security Policy headers can provide an additional defense-in-depth measure to mitigate the impact of potential XSS attacks. Security teams should conduct thorough vulnerability assessments of all installed WordPress plugins and themes, particularly focusing on those that process user input and generate dynamic content. The ATT&CK framework categorizes this vulnerability under T1203 - Exploitation for Client Execution, emphasizing the need for robust application security controls and regular security testing to prevent exploitation. Organizations should also consider implementing Web Application Firewalls and monitoring systems to detect and prevent exploitation attempts targeting known XSS vulnerabilities in their web applications.