CVE-2021-27916
📋 TL;DR
CVE-2021-27916 is a path traversal vulnerability in Mautic's GrapesJS builder that allows authenticated users to delete arbitrary files outside intended directories. This affects all Mautic instances with vulnerable versions, regardless of user privilege level. Attackers could delete critical system files, libraries, or other important files.
💻 Affected Systems
- Mautic
📦 What is this software?
Mautic by Acquia
Mautic by Acquia
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise through deletion of critical system files, leading to service disruption, data loss, or enabling further attacks by removing security controls.
Likely Case
Unauthorized deletion of application files leading to service disruption, data loss, or privilege escalation by removing security components.
If Mitigated
Limited impact if proper file permissions and access controls restrict deletion capabilities, though authenticated users could still cause some disruption.
🎯 Exploit Status
Exploitation requires authenticated access but is straightforward once authenticated. Public proof-of-concept exists in the advisory.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 4.0.0 and later
Vendor Advisory: https://github.com/mautic/mautic/security/advisories/GHSA-9fcx-cv56-w58p
Restart Required: No
Instructions:
1. Backup your Mautic instance and database. 2. Update to Mautic 4.0.0 or later. 3. Verify the update completed successfully. 4. Test application functionality.
🔧 Temporary Workarounds
Restrict file deletion permissions
linuxSet strict file permissions to prevent deletion of critical files outside media directories
chmod -R 755 /path/to/mautic
chown -R www-data:www-data /path/to/mautic
Disable vulnerable component
allDisable or restrict access to the GrapesJS builder if not essential
🧯 If You Can't Patch
- Restrict user access to minimum necessary privileges
- Implement strict file system monitoring and alerting for deletion attempts
🔍 How to Verify
Check if Vulnerable:
Check Mautic version in admin panel or via composer show mautic/coreCheck Version:
composer show mautic/core | grep versionsVerify Fix Applied:
Verify version is 4.0.0 or later and test file deletion functionality📡 Detection & Monitoring
Log Indicators:
- Unusual file deletion events outside media directories
- Multiple failed file access attempts
- User activity logs showing file deletion patterns
Network Indicators:
- HTTP requests to file deletion endpoints with path traversal patterns
SIEM Query:
source="mautic_logs" AND (event="file_deletion" OR action="delete") AND path NOT CONTAINS "/media/"