CVE-2025-64203
📋 TL;DR
This is a reflected cross-site scripting (XSS) vulnerability in the Mailster WordPress plugin that allows attackers to inject malicious scripts into web pages. Attackers can craft malicious URLs that, when visited by users, execute arbitrary JavaScript in the victim's browser context. This affects all WordPress sites running Mailster plugin versions before 4.1.14.
💻 Affected Systems
- WordPress Mailster 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 steal session cookies, perform actions as authenticated users, redirect to malicious sites, or install malware on visitor systems.
Likely Case
Attackers typically use this to steal session cookies to hijack administrator accounts, deface websites, or redirect users to phishing pages.
If Mitigated
With proper input validation and output encoding, malicious scripts would be neutralized before reaching users' browsers.
🎯 Exploit Status
Reflected XSS vulnerabilities are commonly exploited through phishing emails or malicious links. No authentication required to trigger the vulnerability.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 4.1.14
Vendor Advisory: https://patchstack.com/database/Wordpress/Plugin/mailster/vulnerability/wordpress-mailster-plugin-4-1-14-cross-site-scripting-xss-vulnerability?_s_id=cve
Restart Required: No
Instructions:
1. Log into WordPress admin panel. 2. Go to Plugins → Installed Plugins. 3. Find Mailster and click 'Update Now'. 4. Verify version shows 4.1.14 or higher.
🔧 Temporary Workarounds
Temporary Disable Plugin
allDisable Mailster plugin until patched
wp plugin deactivate mailster
Web Application Firewall Rules
allAdd WAF rules to block XSS payloads targeting Mailster endpoints
🧯 If You Can't Patch
- Implement Content Security Policy (CSP) headers to restrict script execution
- Use web application firewall to filter malicious input patterns
🔍 How to Verify
Check if Vulnerable:
Check WordPress admin → Plugins → Installed Plugins → Mailster version numberCheck Version:
wp plugin list --name=mailster --field=versionVerify Fix Applied:
Verify Mailster version is 4.1.14 or higher in WordPress admin panel📡 Detection & Monitoring
Log Indicators:
- Unusual GET/POST requests to Mailster endpoints with script tags or JavaScript payloads
- Multiple failed XSS attempts in web server logs
Network Indicators:
- HTTP requests containing <script>, javascript:, or encoded XSS payloads in URL parameters
SIEM Query:
source="web_server_logs" AND (uri="*mailster*" AND (content="*<script>*" OR content="*javascript:*" OR content="*onerror=*"))