CVE-2020-29553
📋 TL;DR
This CSRF vulnerability in Grav CMS Scheduler allows attackers to trick authenticated administrators into executing arbitrary system commands by visiting a malicious website. The vulnerability affects Grav CMS installations with admin access enabled. Successful exploitation requires an admin to be logged in and visit a malicious page.
💻 Affected Systems
- Grav CMS
📦 What is this software?
Grav Cms by Getgrav
Grav Cms by Getgrav
Grav Cms by Getgrav
Grav Cms by Getgrav
Grav Cms by Getgrav
Grav Cms by Getgrav
Grav Cms by Getgrav
Grav Cms by Getgrav
Grav Cms by Getgrav
Grav Cms by Getgrav
Grav Cms by Getgrav
Grav Cms by Getgrav
Grav Cms by Getgrav
Grav Cms by Getgrav
Grav Cms by Getgrav
Grav Cms by Getgrav
Grav Cms by Getgrav
Grav Cms by Getgrav
Grav Cms by Getgrav
Grav Cms by Getgrav
Grav Cms by Getgrav
Grav Cms by Getgrav
Grav Cms by Getgrav
Grav Cms by Getgrav
Grav Cms by Getgrav
Grav Cms by Getgrav
Grav Cms by Getgrav
Grav Cms by Getgrav
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise via remote code execution, allowing attackers to execute arbitrary commands with the web server's privileges, potentially leading to data theft, system takeover, or lateral movement.
Likely Case
Attackers execute limited system commands to establish persistence, exfiltrate data, or deploy malware, typically targeting the web server's user context.
If Mitigated
With proper CSRF protections and admin session management, exploitation is prevented even if admin visits malicious sites.
🎯 Exploit Status
Exploitation requires social engineering to trick admin into visiting malicious site while authenticated.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.7.0-rc.18 and later
Vendor Advisory: https://github.com/getgrav/grav/releases/tag/1.7.0-rc.18
Restart Required: No
Instructions:
1. Backup your Grav installation. 2. Update to Grav CMS 1.7.0-rc.18 or later via package manager or manual download. 3. Clear cache if needed.
🔧 Temporary Workarounds
CSRF Protection Enhancement
allImplement additional CSRF tokens and validation for admin actions
Admin Access Restriction
allRestrict admin panel access to specific IP addresses or VPN
🧯 If You Can't Patch
- Implement strict SameSite cookie policies and CSRF protection headers
- Use separate browser profiles for admin access and general browsing
🔍 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 1.7.0-rc.18 or later and test CSRF protection on scheduler endpoints📡 Detection & Monitoring
Log Indicators:
- Unexpected scheduler command executions
- Admin panel access from unusual IPs followed by system commands
Network Indicators:
- Outbound connections from web server to suspicious domains after admin login
SIEM Query:
source="grav-admin.log" AND ("scheduler" OR "command") AND status="200"