CVE-2023-40203
📋 TL;DR
This CVE describes a Missing Authorization vulnerability in the MailChimp Forms by MailMunch WordPress plugin that allows attackers to exploit incorrectly configured access control security levels. The vulnerability affects all versions up to 3.1.4, potentially allowing unauthorized users to perform actions they shouldn't be able to.
💻 Affected Systems
- MailChimp Forms by MailMunch WordPress Plugin
📦 What is this software?
Mailchimp Forms by Mailmunch
⚠️ Risk & Real-World Impact
Worst Case
Attackers could modify plugin settings, access user data collected through forms, or potentially inject malicious code into forms.
Likely Case
Unauthorized users could modify form configurations, potentially redirecting form submissions or accessing collected email addresses.
If Mitigated
With proper access controls, only authenticated administrators could modify plugin settings.
🎯 Exploit Status
The vulnerability involves missing authorization checks, which typically means simple HTTP requests can trigger unauthorized actions.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Versions after 3.1.4
Restart Required: No
Instructions:
1. Log into WordPress admin panel
2. Go to Plugins → Installed Plugins
3. Find 'MailChimp Forms by MailMunch'
4. Click 'Update Now' if available
5. If no update available, deactivate and delete the plugin
6. Install the latest version from WordPress repository
🔧 Temporary Workarounds
Temporary Deactivation
allDeactivate the plugin until patched version is available
wp plugin deactivate mailchimp-forms-by-mailmunch
🧯 If You Can't Patch
- Remove the plugin entirely and use alternative form solutions
- Implement web application firewall rules to block unauthorized access to plugin endpoints
🔍 How to Verify
Check if Vulnerable:
Check WordPress admin panel → Plugins → MailChimp Forms by MailMunch → Version. If version is 3.1.4 or lower, you are vulnerable.Check Version:
wp plugin get mailchimp-forms-by-mailmunch --field=versionVerify Fix Applied:
After updating, verify the plugin version is higher than 3.1.4 in WordPress admin panel.📡 Detection & Monitoring
Log Indicators:
- Unauthorized POST requests to /wp-admin/admin-ajax.php with mailmunch-related actions
- Multiple failed authorization attempts on plugin endpoints
Network Indicators:
- Unusual traffic to /wp-admin/admin-ajax.php with mailmunch parameters from unauthenticated sources
SIEM Query:
source="web_server" AND (uri="/wp-admin/admin-ajax.php" AND parameters CONTAINS "mailmunch") AND NOT (user_agent CONTAINS "wp-admin")