CVE-2026-25430: Mailchimp Integration Auth Bypass Flaw

CVE-2026-25430 Overview

CVE-2026-25430 is a Missing Authorization vulnerability affecting the CRM Perks Integration for Mailchimp and Contact Form 7, WPForms, Elementor, Ninja Forms WordPress plugin (cf7-mailchimp). This Broken Access Control vulnerability allows attackers with low-level privileges to exploit incorrectly configured access control security levels, potentially gaining unauthorized access to plugin functionality that should be restricted to administrators.

The vulnerability stems from missing capability checks on sensitive plugin functions, allowing authenticated users with minimal privileges (such as subscribers) to perform actions that should require administrative access. This could lead to unauthorized modifications to Mailchimp integration settings, data manipulation, or exposure of connected service configurations.

Critical Impact

Authenticated attackers with low privileges can bypass authorization controls to modify plugin settings and potentially compromise Mailchimp integrations, affecting form submissions and marketing data flows.

Affected Products

• Integration for Mailchimp and Contact Form 7, WPForms, Elementor, Ninja Forms plugin versions up to and including 1.2.2
• WordPress sites using the cf7-mailchimp plugin
• Sites integrating Contact Form 7, WPForms, Elementor Forms, or Ninja Forms with Mailchimp

Discovery Timeline

• 2026-03-25 - CVE-2026-25430 published to NVD
• 2026-03-26 - Last updated in NVD database

Technical Details for CVE-2026-25430

Vulnerability Analysis

This vulnerability is classified as CWE-862 (Missing Authorization), which occurs when a software component does not perform an authorization check when an actor attempts to access a resource or perform an action. In the context of WordPress plugins, this typically manifests when AJAX handlers or admin functions fail to verify that the requesting user has the appropriate capability level.

The cf7-mailchimp plugin provides integration between popular WordPress form plugins and the Mailchimp email marketing platform. The vulnerability allows attackers to bypass intended access restrictions by directly invoking plugin functions without proper authorization verification.

Root Cause

The root cause is the absence of capability checks (such as current_user_can()) in WordPress plugin functions that handle sensitive operations. When plugin endpoints or AJAX handlers process requests without verifying user permissions, any authenticated user can invoke these functions regardless of their assigned role.

In WordPress development, proper authorization requires checking capabilities like manage_options or custom capabilities before executing administrative functions. The missing authorization in this plugin allows low-privileged users to access functionality intended only for administrators.

Attack Vector

The attack can be executed remotely over the network by any authenticated WordPress user. The attacker requires only a valid user account with minimal privileges (e.g., Subscriber role). The attack does not require user interaction and can be performed directly against the vulnerable plugin endpoints.

An attacker could:

1. Authenticate to the WordPress site with a low-privilege account
2. Identify unprotected AJAX handlers or admin functions within the plugin
3. Craft requests to these endpoints to modify Mailchimp integration settings
4. Potentially disconnect or reconfigure form-to-Mailchimp mappings
5. Modify subscriber list assignments or API key configurations

For detailed technical information about this vulnerability, refer to the Patchstack security advisory.

Detection Methods for CVE-2026-25430

Indicators of Compromise

• Unexpected modifications to Mailchimp integration settings without administrator action
• Plugin configuration changes in the database wp_options table related to cf7-mailchimp
• AJAX requests to plugin endpoints from users with subscriber or contributor roles
• Unauthorized access patterns in WordPress debug logs showing capability bypass attempts

Detection Strategies

• Monitor WordPress admin-ajax.php requests for cf7-mailchimp actions from non-administrator users
• Implement logging for plugin settings modifications and correlate with user role data
• Review access logs for POST requests to wp-admin endpoints by low-privilege authenticated sessions
• Enable WordPress debug logging to capture unauthorized access attempts

Monitoring Recommendations

• Deploy web application firewall (WAF) rules to monitor and alert on suspicious admin-ajax.php activity
• Implement user activity logging plugins to track settings changes across all WordPress plugins
• Configure SIEM alerts for patterns indicating broken access control exploitation
• Regularly audit user roles and remove unnecessary accounts to reduce attack surface

How to Mitigate CVE-2026-25430

Immediate Actions Required

• Update the Integration for Mailchimp and Contact Form 7 plugin to a patched version above 1.2.2
• Review plugin settings and Mailchimp integration configurations for unauthorized changes
• Audit user accounts and remove unnecessary low-privilege users
• Consider temporarily disabling the plugin until a patch can be applied

Patch Information

Affected versions include all releases from the initial version through 1.2.2. Site administrators should check for updates via the WordPress plugin repository or contact CRM Perks for the latest patched version. Verify the patch includes proper capability checks on all administrative functions.

For vulnerability details and remediation guidance, see the Patchstack vulnerability database entry.

Workarounds

• Restrict WordPress user registration to prevent unauthorized account creation
• Implement additional access controls via security plugins that enforce capability checks
• Use a web application firewall to block unauthorized requests to plugin AJAX handlers
• Temporarily deactivate the cf7-mailchimp plugin if the site does not require immediate Mailchimp integration

# Check installed plugin version via WP-CLI
wp plugin list --name=cf7-mailchimp --fields=name,version,status

# Update plugin to latest version
wp plugin update cf7-mailchimp

# Alternatively, deactivate until patch is applied
wp plugin deactivate cf7-mailchimp