CVE-2023-34251
📋 TL;DR
CVE-2023-34251 is a server-side template injection vulnerability in Grav CMS that allows authenticated users with page editing privileges to execute arbitrary PHP code. This leads to remote code execution on the server, potentially compromising the entire system. All Grav installations prior to version 1.7.42 are affected.
💻 Affected Systems
- Grav CMS
📦 What is this software?
Grav by Getgrav
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with attacker gaining full control over the web server, accessing sensitive data, installing backdoors, and pivoting to other systems.
Likely Case
Attacker with page editing privileges executes arbitrary code to steal credentials, modify content, or install malware on the server.
If Mitigated
Limited impact if proper access controls restrict page editing to trusted administrators only.
🎯 Exploit Status
Exploitation requires authenticated user with page editing privileges; proof-of-concept code is publicly available in advisory.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.7.42
Vendor Advisory: https://github.com/getgrav/grav/security/advisories/GHSA-f9jf-4cp4-4fq5
Restart Required: No
Instructions:
1. Backup your Grav installation. 2. Update Grav to version 1.7.42 or later via package manager or manual download. 3. Clear cache if needed.
🔧 Temporary Workarounds
Restrict Page Editing Privileges
allTemporarily remove page editing capabilities from non-essential users until patching.
🧯 If You Can't Patch
- Implement strict access controls to limit page editing to only essential, trusted administrators
- Monitor administrator accounts and page edit logs for suspicious activity
🔍 How to Verify
Check if Vulnerable:
Check Grav version in admin panel or via CLI: php bin/grav versionCheck Version:
php bin/grav versionVerify Fix Applied:
Confirm version is 1.7.42 or higher using same commands📡 Detection & Monitoring
Log Indicators:
- Unusual page edit activity from admin accounts
- PHP execution attempts in template files
- Suspicious file modifications
Network Indicators:
- Unexpected outbound connections from web server
- Command and control traffic patterns
SIEM Query:
source="grav_logs" AND (event="page_edit" OR event="template_modify") AND user NOT IN ["trusted_admins"]🔗 References
- https://github.com/getgrav/grav/blob/develop/system/src/Grav/Common/Twig/Extension/GravExtension.php#L174
- https://github.com/getgrav/grav/commit/9d01140a63c77075ef09b26ef57cf186138151a5
- https://github.com/getgrav/grav/security/advisories/GHSA-f9jf-4cp4-4fq5
- https://github.com/getgrav/grav/blob/develop/system/src/Grav/Common/Twig/Extension/GravExtension.php#L174
- https://github.com/getgrav/grav/commit/9d01140a63c77075ef09b26ef57cf186138151a5
- https://github.com/getgrav/grav/security/advisories/GHSA-f9jf-4cp4-4fq5
