CVE-2024-11782
📋 TL;DR
The WP Mailster WordPress plugin has a stored XSS vulnerability that allows authenticated attackers with contributor-level access or higher to inject malicious scripts into website pages. These scripts execute when users visit the compromised pages, potentially stealing credentials or performing unauthorized actions. All WordPress sites using WP Mailster versions up to 1.8.17.0 are affected.
💻 Affected Systems
- WP Mailster WordPress Plugin
📦 What is this software?
Wp Mailster by Wpmailster
⚠️ Risk & Real-World Impact
Worst Case
Attackers could steal administrator credentials, take over the WordPress site, deface pages, redirect users to malicious sites, or install backdoors for persistent access.
Likely Case
Attackers with contributor access inject malicious scripts to steal user session cookies, perform actions as authenticated users, or display phishing content to visitors.
If Mitigated
With proper user role management and input validation, the attack surface is reduced, but the vulnerability still exists in the codebase.
🎯 Exploit Status
Exploitation requires authenticated access but is technically simple once an attacker has contributor privileges.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.8.18.0 or later
Vendor Advisory: https://plugins.trac.wordpress.org/changeset/3198497/wp-mailster/trunk/mailster/subscr/SubscriberPlugin.php
Restart Required: No
Instructions:
1. Log into WordPress admin panel. 2. Navigate to Plugins > Installed Plugins. 3. Find WP Mailster and click 'Update Now'. 4. Verify update to version 1.8.18.0 or higher.
🔧 Temporary Workarounds
Remove Contributor Access
allTemporarily remove contributor-level access from untrusted users until patching is complete.
Disable Plugin
allDeactivate WP Mailster plugin if not essential for site functionality.
🧯 If You Can't Patch
- Implement strict user role management to limit contributor access to trusted users only.
- Deploy a web application firewall (WAF) with XSS protection rules to block exploitation attempts.
🔍 How to Verify
Check if Vulnerable:
Check WordPress admin panel > Plugins > Installed Plugins for WP Mailster version. If version is 1.8.17.0 or lower, you are vulnerable.Check Version:
wp plugin list --name=wp-mailster --field=versionVerify Fix Applied:
After updating, verify WP Mailster version is 1.8.18.0 or higher in WordPress admin panel.📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to WordPress admin-ajax.php with mst_subscribe parameters
- Multiple failed login attempts followed by successful contributor-level login
Network Indicators:
- HTTP requests containing malicious script tags in mst_subscribe shortcode parameters
SIEM Query:
source="wordpress.log" AND ("mst_subscribe" AND ("<script>" OR "javascript:" OR "onerror="))🔗 References
- https://plugins.trac.wordpress.org/browser/wp-mailster/tags/1.8.17.0/mailster/subscr/SubscriberPlugin.php#L216
- https://plugins.trac.wordpress.org/changeset/3198497/wp-mailster/trunk/mailster/subscr/SubscriberPlugin.php
- https://www.wordfence.com/threat-intel/vulnerabilities/id/909beed4-06a9-4ec4-bf00-4072a38af82b?source=cve
