CVE-2025-23703
📋 TL;DR
This CVE describes a Cross-Site Request Forgery (CSRF) vulnerability in the Free MailClient FMC WordPress plugin that can lead to Stored Cross-Site Scripting (XSS). Attackers can trick authenticated administrators into executing malicious actions that inject persistent scripts into the website. WordPress sites using vulnerable versions of this plugin are affected.
💻 Affected Systems
- Free MailClient FMC WordPress Plugin
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Attackers could inject malicious JavaScript that steals administrator credentials, redirects users to phishing sites, or takes full control of the WordPress site when administrators view infected pages.
Likely Case
Attackers would typically use this to inject advertising scripts, cryptocurrency miners, or credential-stealing payloads that affect all visitors to the compromised site.
If Mitigated
With proper CSRF protections and content security policies, the attack would fail or have limited impact even if attempted.
🎯 Exploit Status
Exploitation requires social engineering to trick an authenticated administrator into clicking a malicious link. The CSRF leads to stored XSS payload injection.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check with plugin developer for updated version
Restart Required: No
Instructions:
1. Log into WordPress admin panel. 2. Navigate to Plugins → Installed Plugins. 3. Locate Free MailClient FMC. 4. Check for available updates or remove if no update exists. 5. If no patch is available, disable and remove the plugin.
🔧 Temporary Workarounds
Implement CSRF Tokens
WordPressAdd CSRF protection tokens to all plugin forms and actions
Requires custom PHP development to implement nonce verification in plugin code
Content Security Policy
allImplement a strict Content Security Policy header to prevent XSS execution
Add to .htaccess: Header set Content-Security-Policy "default-src 'self'; script-src 'self'"
Or implement via WordPress security plugin
🧯 If You Can't Patch
- Disable and remove the Free MailClient FMC plugin from all WordPress installations
- Implement web application firewall rules to block suspicious POST requests to plugin endpoints
🔍 How to Verify
Check if Vulnerable:
Check WordPress admin → Plugins → Installed Plugins for Free MailClient FMC version 1.0 or earlierCheck Version:
wp plugin list --name=mailclient --field=version (if WP-CLI installed) or check WordPress admin interfaceVerify Fix Applied:
Verify the plugin is either updated to a patched version or completely removed from the plugins directory📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to /wp-admin/admin-ajax.php or plugin-specific endpoints
- Multiple failed CSRF token validations in WordPress debug logs
Network Indicators:
- Unexpected JavaScript injections in plugin settings or email content
- External script loads from unfamiliar domains in page responses
SIEM Query:
source="wordpress.log" AND ("mailclient" OR "fmc") AND ("POST" OR "admin-ajax")