CVE-2020-26108
📋 TL;DR
CVE-2020-26108 is a critical file-extension dispatching vulnerability in cPanel that allows remote attackers to execute arbitrary code. This affects cPanel web hosting control panel installations, potentially compromising entire hosting servers and all hosted websites. Attackers can exploit this to gain full control of affected systems.
💻 Affected Systems
- cPanel
📦 What is this software?
Cpanel by Cpanel
⚠️ Risk & Real-World Impact
Worst Case
Complete server compromise leading to data theft, ransomware deployment, lateral movement to other systems, and persistent backdoor installation.
Likely Case
Attackers gain shell access to the cPanel server, allowing them to modify websites, steal sensitive data, and use the server for further attacks.
If Mitigated
Limited impact with proper network segmentation, but still significant risk to the cPanel instance itself.
🎯 Exploit Status
Exploitation is straightforward with publicly available proof-of-concept code. Attackers can easily automate attacks against vulnerable systems.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 88.0.13 and later
Vendor Advisory: https://docs.cpanel.net/changelogs/88-change-log/
Restart Required: No
Instructions:
1. Log into WHM as root. 2. Navigate to 'Update cPanel & WHM'. 3. Click 'Update to Latest Version'. 4. Alternatively, run: /usr/local/cpanel/scripts/upcp --force
🔧 Temporary Workarounds
Temporary access restriction
linuxRestrict access to cPanel/WHM to trusted IP addresses only
iptables -A INPUT -p tcp --dport 2083 -s TRUSTED_IP -j ACCEPT
iptables -A INPUT -p tcp --dport 2083 -j DROP
🧯 If You Can't Patch
- Immediately restrict network access to cPanel/WHM ports (2083, 2087, 2086) to only trusted IP addresses
- Implement web application firewall rules to block suspicious file extension requests
🔍 How to Verify
Check if Vulnerable:
Check cPanel version: /usr/local/cpanel/cpanel -V | grep '^88\.' and verify it's below 88.0.13Check Version:
/usr/local/cpanel/cpanel -VVerify Fix Applied:
Verify version is 88.0.13 or higher: /usr/local/cpanel/cpanel -V📡 Detection & Monitoring
Log Indicators:
- Unusual file extension requests in cPanel logs
- Suspicious process execution from web user context
- Unexpected file uploads or modifications
Network Indicators:
- Exploitation attempts targeting cPanel ports with unusual file extensions
- Outbound connections from cPanel server to unknown IPs
SIEM Query:
source="cpanel.log" AND ("unusual_extension" OR "file_upload" OR "execution")