CVE-2021-46361
📋 TL;DR
This vulnerability in Magnolia CMS allows attackers to bypass security restrictions in the FreeMarker template engine and execute arbitrary code via specially crafted payloads. It affects Magnolia CMS v6.2.11 and earlier versions, potentially enabling remote code execution on affected systems.
💻 Affected Systems
- Magnolia CMS
📦 What is this software?
Magnolia Cms by Magnolia Cms
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise with attacker gaining complete control over the Magnolia CMS server, allowing data theft, defacement, or use as a pivot point into internal networks.
Likely Case
Remote code execution leading to website defacement, data exfiltration, or installation of backdoors and malware.
If Mitigated
Limited impact with proper network segmentation, web application firewalls, and strict input validation in place.
🎯 Exploit Status
Exploitation requires sending crafted FreeMarker payloads to vulnerable endpoints.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: v6.2.12
Vendor Advisory: https://docs.magnolia-cms.com/product-docs/6.2/Releases/Release-notes-for-Magnolia-CMS-6.2.12.html#_security_advisory
Restart Required: Yes
Instructions:
1. Backup your Magnolia CMS instance and database. 2. Download Magnolia CMS v6.2.12 or later from the official vendor. 3. Follow the upgrade instructions in the Magnolia documentation. 4. Restart the Magnolia CMS service.
🔧 Temporary Workarounds
Web Application Firewall Rule
allImplement WAF rules to block suspicious FreeMarker template patterns and payloads.
Input Validation Filter
allAdd custom input validation to sanitize FreeMarker template inputs before processing.
🧯 If You Can't Patch
- Isolate the Magnolia CMS instance behind a reverse proxy with strict input validation
- Disable or restrict access to FreeMarker template editing functionality if not required
🔍 How to Verify
Check if Vulnerable:
Check the Magnolia CMS version in the admin interface or by examining the installation directory. Versions 6.2.11 and below are vulnerable.Check Version:
Check the Magnolia admin panel or examine the magnolia.properties file in the installation directory.Verify Fix Applied:
Verify the Magnolia CMS version is 6.2.12 or higher after patching.📡 Detection & Monitoring
Log Indicators:
- Unusual FreeMarker template processing errors
- Suspicious POST requests containing FreeMarker syntax
- Unexpected system command execution in logs
Network Indicators:
- HTTP requests with FreeMarker payloads to Magnolia endpoints
- Unusual outbound connections from Magnolia server
SIEM Query:
source="magnolia" AND (message="*FreeMarker*" OR message="*template*" OR message="*exec*" OR message="*Runtime*" OR message="*ProcessBuilder*")🔗 References
- https://docs.magnolia-cms.com/product-docs/6.2/Releases/Release-notes-for-Magnolia-CMS-6.2.12.html#_security_advisory
- https://github.com/DrunkenShells/Disclosures/tree/master/CVE-2021-46361-FreeMarker%20Bypass-Magnolia%20CMS
- https://docs.magnolia-cms.com/product-docs/6.2/Releases/Release-notes-for-Magnolia-CMS-6.2.12.html#_security_advisory
- https://github.com/DrunkenShells/Disclosures/tree/master/CVE-2021-46361-FreeMarker%20Bypass-Magnolia%20CMS
