CVE-2021-47900
📋 TL;DR
CVE-2021-47900 is a critical remote code execution vulnerability in Gila CMS that allows unauthenticated attackers to execute arbitrary system commands by injecting PHP code in HTTP headers. This affects all Gila CMS installations prior to version 2.0.0. Attackers can compromise the entire server through crafted requests to the admin endpoint.
💻 Affected Systems
- Gila CMS
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Complete server compromise allowing attackers to install malware, steal data, pivot to internal networks, or use the server for further attacks.
Likely Case
Attackers gain shell access to the web server, deface websites, install cryptocurrency miners, or establish persistent backdoors.
If Mitigated
Limited impact if proper network segmentation, web application firewalls, and monitoring are in place to detect and block exploitation attempts.
🎯 Exploit Status
Exploit code is publicly available on Exploit-DB and other sources. Attack requires only HTTP requests with crafted headers.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2.0.0
Vendor Advisory: https://github.com/GilaCMS/gila/releases/tag/v2.0.0
Restart Required: No
Instructions:
1. Backup your current Gila CMS installation and database. 2. Download Gila CMS version 2.0.0 or later from the official repository. 3. Replace all files with the new version, preserving configuration files. 4. Verify the update by checking the version in the admin panel.
🔧 Temporary Workarounds
Web Application Firewall Rule
allBlock or sanitize User-Agent headers containing PHP code or shell_exec patterns
# Example ModSecurity rule: SecRule REQUEST_HEADERS:User-Agent "(shell_exec|php://|\$_)|" "phase:1,deny,id:1001"
Restrict Admin Endpoint Access
allBlock external access to /admin/ paths using web server configuration
# Apache: <Location /admin/>
Order deny,allow
Deny from all
Allow from 192.168.1.0/24
</Location>
# Nginx: location /admin/ { deny all; }
🧯 If You Can't Patch
- Immediately restrict network access to the Gila CMS instance using firewall rules to allow only trusted IPs.
- Implement a web application firewall with rules to detect and block exploitation attempts targeting this vulnerability.
🔍 How to Verify
Check if Vulnerable:
Check if Gila CMS version is below 2.0.0 by examining the version in admin panel or checking the gila/version.php file.Check Version:
grep -r "define.*GILA_VERSION" /path/to/gila/ || cat /path/to/gila/version.phpVerify Fix Applied:
After updating, verify the version shows 2.0.0 or higher in the admin panel and test that crafted User-Agent headers no longer execute commands.📡 Detection & Monitoring
Log Indicators:
- HTTP requests to /admin/ paths with unusual User-Agent headers containing PHP code patterns
- Web server logs showing shell_exec or system command execution
Network Indicators:
- HTTP requests with User-Agent headers containing shell_exec(), system(), or eval() patterns
- Unusual outbound connections from the web server to external IPs
SIEM Query:
source="web_logs" AND (uri_path="/admin/*" AND user_agent="*shell_exec*" OR user_agent="*php://*")