CVE-2025-12974: Gravity Forms WordPress Plugin RCE Flaw

CVE-2025-12974 Overview

CVE-2025-12974 is an arbitrary file upload vulnerability affecting the Gravity Forms plugin for WordPress. The vulnerability exists in the legacy chunked upload mechanism where improper file type validation allows unauthenticated attackers to upload malicious .phar files. This flaw stems from an incomplete extension blacklist that fails to block .phar files, which can be processed as PHP code under certain server configurations. If successfully exploited, this vulnerability can lead to remote code execution (RCE) on the affected server.

Critical Impact

Unauthenticated attackers can achieve remote code execution by uploading malicious .phar files through the vulnerable chunked upload mechanism, potentially leading to complete server compromise.

Affected Products

• Gravity Forms WordPress Plugin versions up to and including 2.9.21.1
• WordPress installations using vulnerable Gravity Forms versions
• Web servers configured to process .phar files as PHP

Discovery Timeline

• 2025-11-18 - CVE-2025-12974 published to NVD
• 2025-11-18 - Last updated in NVD database

Technical Details for CVE-2025-12974

Vulnerability Analysis

This vulnerability is classified as CWE-434 (Unrestricted Upload of File with Dangerous Type). The flaw exists within Gravity Forms' legacy chunked upload mechanism, which processes file uploads in segments. While the plugin implements an extension blacklist to prevent dangerous file types from being uploaded, this blacklist does not include .phar (PHP Archive) files.

The vulnerability requires specific conditions to achieve remote code execution: the web server must be configured to process .phar files as PHP through file handler mapping or similar configuration. Additionally, attackers must be able to discover or enumerate the upload path where the malicious file is stored.

Root Cause

The root cause of this vulnerability lies in the incomplete file extension blacklist implementation within the Gravity Forms plugin. The validation logic in the upload handler fails to account for .phar files as a potentially dangerous file type. PHP Archive (.phar) files can contain executable PHP code and, when properly handled by the web server, can execute arbitrary commands on the system.

The vulnerable code paths can be examined in the Common.php and Upload.php files in the Gravity Forms repository.

Attack Vector

The attack vector for this vulnerability is network-based and requires no authentication or user interaction. An attacker can exploit this vulnerability by:

1. Identifying a WordPress site running a vulnerable version of Gravity Forms
2. Crafting a malicious .phar file containing PHP code designed to execute commands
3. Using the legacy chunked upload mechanism to upload the file, bypassing the extension blacklist
4. Discovering or enumerating the upload path location
5. Accessing the uploaded .phar file to trigger code execution (requires server to process .phar as PHP)

The attack complexity is considered high due to the requirement for the server to be specifically configured to process .phar files as PHP and the need to discover the upload path.

Detection Methods for CVE-2025-12974

Indicators of Compromise

• Presence of unexpected .phar files in WordPress upload directories, particularly within Gravity Forms upload paths
• Web server access logs showing requests to .phar files in upload directories
• Suspicious chunked upload requests targeting the Gravity Forms upload endpoints
• Unusual PHP process activity or unexpected outbound connections from the web server

Detection Strategies

• Monitor file system changes for .phar file creation in WordPress directories, especially /wp-content/uploads/ and Gravity Forms specific paths
• Implement web application firewall (WAF) rules to detect and block upload attempts for .phar files
• Review web server logs for POST requests to Gravity Forms upload endpoints followed by GET requests to .phar files
• Deploy file integrity monitoring solutions to detect unauthorized file additions

Monitoring Recommendations

• Enable detailed logging on web servers and WordPress installations to capture upload activity
• Configure alerting for any .phar file access attempts in web directories
• Monitor for signs of webshell activity including unusual command execution patterns
• Implement network monitoring to detect potential data exfiltration following successful exploitation

How to Mitigate CVE-2025-12974

Immediate Actions Required

• Update Gravity Forms plugin to the latest patched version immediately
• Audit existing upload directories for any suspicious .phar files and remove them
• Review web server configuration and disable .phar file processing if not required
• Implement additional file upload validation at the web server level to block .phar extensions

Patch Information

The Gravity Forms development team has addressed this vulnerability in versions newer than 2.9.21.1. Administrators should update to the latest available version as soon as possible. Detailed patch information and changelog can be found in the Gravity Forms Change Log. Additional vulnerability details are available through the Wordfence Vulnerability Overview.

Workarounds

• Configure the web server to not process .phar files as PHP by removing or commenting out .phar handler mappings in Apache or Nginx configurations
• Implement additional server-side validation to explicitly block .phar file uploads
• Use a web application firewall to filter upload requests containing .phar files
• Restrict access to upload directories through .htaccess rules or Nginx configuration blocks

# Apache configuration to disable .phar file processing
# Add to your virtual host or .htaccess file
<FilesMatch "\.phar$">
    SetHandler none
    SetHandler default-handler
    Options -ExecCGI
    RemoveHandler .phar
</FilesMatch>

# Nginx configuration to block .phar file execution
# Add to your server block
location ~* \.phar$ {
    deny all;
    return 403;
}