CVE-2025-8289: WordPress Redirection CF7 RCE Vulnerability

CVE-2025-8289 Overview

The Redirection for Contact Form 7 plugin for WordPress contains a PHP Object Injection vulnerability in all versions up to and including 3.2.4. This vulnerability exists in the delete_associated_files function due to unsafe deserialization of untrusted input. The flaw allows unauthenticated attackers to inject malicious PHP objects, potentially leading to severe consequences depending on the presence of exploitable POP (Property-Oriented Programming) chains in the WordPress installation.

Critical Impact

Unauthenticated attackers can exploit this vulnerability to delete arbitrary files, retrieve sensitive data, or execute code when a suitable POP chain exists. The vulnerability has been confirmed to enable arbitrary file deletion when the Contact Form 7 plugin is installed, which is a requirement for this plugin.

Affected Products

• Redirection for Contact Form 7 plugin versions ≤ 3.2.4
• WordPress sites running PHP version ≤ 8
• Sites with "Redirection For Contact Form 7 Extension - Create Post" extension installed and activated

Discovery Timeline

• 2025-08-20 - CVE-2025-8289 published to NVD
• 2025-08-20 - Last updated in NVD database

Technical Details for CVE-2025-8289

Vulnerability Analysis

This PHP Object Injection vulnerability stems from insecure deserialization practices within the delete_associated_files function located in the class-wpcf7r-save-files.php file. The function processes untrusted input without proper validation, allowing attackers to craft malicious serialized objects that get instantiated during the deserialization process.

The exploitation requires several conditions to be met: a form with a file upload action must exist on the target site, the WordPress installation must be running PHP version 8 or lower, and the "Redirection For Contact Form 7 Extension - Create Post" extension must be installed and activated. While no known POP chain exists within the vulnerable plugin itself, the presence of Contact Form 7 (a required dependency) provides a usable gadget chain that enables arbitrary file deletion.

The attack is network-based but requires specific conditions to be met, including user interaction with a form containing file upload functionality. The vulnerability affects confidentiality, integrity, and availability when successfully exploited in conjunction with a compatible POP chain.

Root Cause

The root cause of CVE-2025-8289 is the use of PHP's unserialize() function on user-controllable data without proper sanitization or validation. The delete_associated_files function in class-wpcf7r-save-files.php accepts serialized data that can be manipulated by attackers to inject arbitrary PHP objects. This is classified as CWE-502 (Deserialization of Untrusted Data).

Attack Vector

The attack vector is network-based and targets WordPress sites with the vulnerable plugin configuration. An unauthenticated attacker can exploit this vulnerability by:

1. Identifying a target WordPress site running the Redirection for Contact Form 7 plugin version 3.2.4 or earlier
2. Locating a form with file upload functionality on the site
3. Crafting a malicious serialized PHP object payload designed to leverage an available POP chain
4. Submitting the payload through the form's file upload mechanism
5. When the delete_associated_files function processes the malicious input, the injected object is instantiated and the POP chain executes

The vulnerability mechanism relies on PHP's native serialization functionality being abused through untrusted input. Detailed technical analysis is available in the Wordfence Vulnerability Analysis. The vulnerable code can be reviewed in the WordPress Plugin Repository.

Detection Methods for CVE-2025-8289

Indicators of Compromise

• Unexpected file deletions on the WordPress site, particularly wp-config.php or other critical files
• Unusual serialized data patterns in web server access logs related to Contact Form 7 submissions
• Error logs showing PHP deserialization warnings or object instantiation failures
• Evidence of unauthorized form submissions with malformed or suspicious file upload data

Detection Strategies

• Monitor web application firewall logs for serialized PHP object patterns in POST requests
• Implement file integrity monitoring to detect unexpected modifications or deletions of WordPress core and configuration files
• Review Contact Form 7 submission logs for anomalous entries or unusual payload patterns
• Deploy WordPress security plugins that can detect insecure deserialization attempts

Monitoring Recommendations

• Enable verbose logging for the Contact Form 7 and Redirection plugins to capture suspicious activity
• Configure alerts for critical file access or deletion events in WordPress directories
• Implement real-time monitoring of form submission endpoints for injection attempts
• Regularly audit installed plugins and extensions to ensure only necessary components are active

How to Mitigate CVE-2025-8289

Immediate Actions Required

• Update the Redirection for Contact Form 7 plugin to a patched version beyond 3.2.4 immediately
• Disable or remove the "Redirection For Contact Form 7 Extension - Create Post" extension if not required for business operations
• Upgrade PHP to version 8.1 or higher as the vulnerability does not affect PHP versions greater than 8
• Implement a Web Application Firewall (WAF) rule to block serialized PHP object patterns in form submissions

Patch Information

Plugin maintainers are expected to release a patched version addressing the insecure deserialization in the delete_associated_files function. Users should monitor the official WordPress plugin repository and the Wordfence Threat Intel page for patch availability announcements. Apply updates as soon as they become available through the WordPress admin dashboard.

Workarounds

• Temporarily deactivate the Redirection for Contact Form 7 plugin until a patch is available if the functionality is not critical
• Remove forms containing file upload actions from public-facing pages as a temporary measure
• Upgrade to PHP 8.1 or newer to eliminate the exploitability of this specific vulnerability
• Implement server-level restrictions to filter potentially malicious serialized data in incoming requests

# Configuration example
# Add to .htaccess to help filter suspicious serialized data patterns
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteCond %{QUERY_STRING} (a|O|s):[0-9]+: [NC,OR]
RewriteCond %{REQUEST_BODY} (a|O|s):[0-9]+:
RewriteRule .* - [F,L]
</IfModule>

# Verify current PHP version
php -v

# Upgrade PHP to version 8.1+ (Ubuntu/Debian example)
sudo apt update
sudo apt install php8.1-fpm php8.1-mysql php8.1-xml