CVE-2025-55211
📋 TL;DR
CVE-2025-55211 allows authenticated FreePBX administrators to execute arbitrary shell commands by manipulating language settings in the framework module. This vulnerability affects FreePBX installations running versions 17.0.19.11 through 17.0.20.99. Attackers with administrative access can gain full system control.
💻 Affected Systems
- FreePBX
📦 What is this software?
Freepbx by Sangoma
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise allowing attackers to install backdoors, exfiltrate data, pivot to other systems, or disrupt telephony services.
Likely Case
Privilege escalation leading to unauthorized system access, data theft, or service disruption by malicious insiders or compromised admin accounts.
If Mitigated
Limited impact if proper access controls, network segmentation, and monitoring are in place to detect and contain exploitation attempts.
🎯 Exploit Status
Exploitation requires authenticated admin access but is straightforward once access is obtained. No public exploit code is available yet.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 17.0.21
Vendor Advisory: https://github.com/FreePBX/security-reporting/security/advisories/GHSA-xg83-m6q5-q24h
Restart Required: Yes
Instructions:
1. Backup your FreePBX configuration. 2. Update FreePBX using the web interface: Admin → Module Admin → Check for updates. 3. Apply all available updates. 4. Restart FreePBX services: 'fwconsole restart' from CLI. 5. Verify version is 17.0.21 or later.
🔧 Temporary Workarounds
Restrict ACP Access
linuxLimit Administrator Control Panel access to trusted IP addresses only using firewall rules.
iptables -A INPUT -p tcp --dport 80 -s TRUSTED_IP -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -s TRUSTED_IP -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP
Disable Unnecessary Admin Accounts
linuxReview and disable any unnecessary administrator accounts to reduce attack surface.
fwconsole ma list | grep framework
Check Admin → User Management for unnecessary accounts
🧯 If You Can't Patch
- Implement strict network segmentation to isolate FreePBX from critical systems.
- Enable detailed logging and monitoring for suspicious admin activities and command execution attempts.
🔍 How to Verify
Check if Vulnerable:
Check FreePBX version: 'fwconsole ma list | grep framework' or via web interface: Admin → Module Admin → Check Online. If version is between 17.0.19.11 and 17.0.20.99, system is vulnerable.Check Version:
fwconsole ma list | grep frameworkVerify Fix Applied:
Verify version is 17.0.21 or later: 'fwconsole ma list | grep framework' should show version >= 17.0.21. Test language change functionality in ACP to ensure no command execution occurs.📡 Detection & Monitoring
Log Indicators:
- Unusual language change requests in FreePBX logs
- Suspicious shell command execution in system logs
- Multiple failed login attempts followed by language changes
Network Indicators:
- Unexpected outbound connections from FreePBX server
- Traffic to unusual ports from FreePBX IP
SIEM Query:
source="freepbx.log" AND ("language change" OR "framework module") AND user="admin" | stats count by src_ip, user