CVE-2024-2242: Contact Form 7 XSS Vulnerability

CVE-2024-2242 Overview

The Contact Form 7 plugin for WordPress contains a Reflected Cross-Site Scripting (XSS) vulnerability in the active-tab parameter. This vulnerability affects all versions up to and including 5.9 and stems from insufficient input sanitization and output escaping. Unauthenticated attackers can exploit this flaw to inject arbitrary web scripts into pages, which execute when a user is tricked into clicking a malicious link.

Contact Form 7 is one of the most popular WordPress plugins, with millions of active installations worldwide, making this vulnerability particularly significant due to its potential reach across the WordPress ecosystem.

Critical Impact

Unauthenticated attackers can inject malicious scripts that execute in victim browsers, potentially leading to session hijacking, credential theft, or malicious redirects affecting WordPress administrators and site visitors.

Affected Products

• Contact Form 7 plugin for WordPress versions up to and including 5.9
• rocklobster contact_form_7 (all vulnerable versions)
• WordPress installations with Contact Form 7 plugin enabled

Discovery Timeline

• 2024-03-13 - CVE-2024-2242 published to NVD
• 2025-01-17 - Last updated in NVD database

Technical Details for CVE-2024-2242

Vulnerability Analysis

This Reflected Cross-Site Scripting vulnerability exists within the Contact Form 7 plugin's administrative interface, specifically in the edit-contact-form.php file. The active-tab parameter fails to properly sanitize user-supplied input before reflecting it back in the page output.

The vulnerability is classified under CWE-79 (Improper Neutralization of Input During Web Page Generation). When exploited, attackers can craft malicious URLs containing JavaScript payloads in the active-tab parameter. If an authenticated administrator clicks such a link, the malicious script executes within their browser session with full access to the WordPress admin context.

The attack requires user interaction (clicking a malicious link), which limits automated exploitation but remains highly effective in targeted social engineering scenarios against WordPress administrators.

Root Cause

The root cause is insufficient input sanitization and output escaping in the handling of the active-tab parameter within the Contact Form 7 administrative interface. The plugin fails to properly validate and encode user-controlled data before including it in the HTML response, allowing script injection through specially crafted URL parameters.

Attack Vector

The attack is conducted over the network and requires no authentication from the attacker's perspective. However, successful exploitation requires social engineering to convince a privileged user (typically a WordPress administrator) to click a malicious link.

A typical attack scenario involves:

1. The attacker crafts a malicious URL targeting a WordPress site using Contact Form 7
2. The URL includes JavaScript payload in the active-tab parameter
3. The attacker delivers the malicious link to a target administrator via phishing email, compromised website, or other social engineering methods
4. When the administrator clicks the link while authenticated, the malicious script executes in their browser
5. The script can then perform actions on behalf of the administrator, steal session tokens, or redirect to malicious sites

The vulnerability exploits the trust relationship between the administrator's browser and the WordPress admin interface. Technical details of the fix can be reviewed in the WordPress Change Log Entry.

Detection Methods for CVE-2024-2242

Indicators of Compromise

• Suspicious URLs in web server access logs containing unusual JavaScript or HTML encoding in the active-tab parameter
• Unexpected administrative actions performed without administrator knowledge or consent
• Browser history or network logs showing malformed URLs targeting /wp-admin/ paths with Contact Form 7 parameters
• Reports from users about unexpected redirects or browser behavior when accessing form administration pages

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect and block requests containing script tags or encoded JavaScript in URL parameters
• Monitor web server access logs for requests to Contact Form 7 admin pages with suspicious active-tab parameter values
• Deploy browser-based XSS protection mechanisms and Content Security Policy (CSP) headers to mitigate script execution
• Use WordPress security plugins to scan for outdated vulnerable plugin versions

Monitoring Recommendations

• Enable detailed logging on WordPress installations to capture all admin interface access attempts with full URL parameters
• Set up automated alerts for detection of encoded or obfuscated content in query string parameters
• Review administrator session activity logs for unusual patterns following link clicks from external sources
• Monitor for unauthorized plugin or user modifications that could indicate successful exploitation

How to Mitigate CVE-2024-2242

Immediate Actions Required

• Update Contact Form 7 plugin to version 5.9.1 or later immediately
• Review WordPress admin access logs for any suspicious activity involving the active-tab parameter
• Implement Content Security Policy headers to restrict inline script execution
• Train administrators to verify URLs before clicking, especially those received via email or external messages

Patch Information

The vulnerability has been addressed by Rocklobster in Contact Form 7 versions after 5.9. The fix implements proper input sanitization and output escaping for the active-tab parameter. Administrators should update to the latest version through the WordPress plugin update mechanism.

The specific code changes can be reviewed in the WordPress plugin repository changeset. Additional vulnerability analysis is available from Wordfence.

Workarounds

• If immediate patching is not possible, restrict access to the WordPress admin interface using IP allowlisting
• Implement a Web Application Firewall with rules to filter potentially malicious XSS payloads in URL parameters
• Consider temporarily disabling Contact Form 7 until the update can be applied in high-risk environments
• Use browser extensions that block or warn about suspicious URL parameters

# WordPress CLI command to update Contact Form 7
wp plugin update contact-form-7

# Verify the installed version after update
wp plugin get contact-form-7 --field=version

# Check for any other outdated plugins
wp plugin list --update=available