CVE-2025-59051: FreePBX Endpoint Manager RCE Vulnerability

CVE-2025-59051 Overview

CVE-2025-59051 is an authenticated OS command injection vulnerability in the FreePBX Endpoint Manager module. The Network Scanning feature exposes nmap functionality through a web interface for network device discovery. Insufficient sanitization of user-supplied input allows authenticated attackers to execute arbitrary operating system commands as the asterisk user. The flaw affects Endpoint Manager 16 before 16.0.92 and 17 before 17.0.6. Exploitation requires authentication with a known username, limiting opportunistic attacks but remaining viable for insiders or attackers with stolen credentials. The vulnerability is classified under [CWE-78] (Improper Neutralization of Special Elements used in an OS Command).

Critical Impact

Authenticated attackers can execute arbitrary OS commands as the asterisk user, enabling lateral movement, telephony service tampering, and potential pivoting into voice infrastructure.

Affected Products

• FreePBX Endpoint Manager 16 prior to 16.0.92
• FreePBX Endpoint Manager 17 prior to 17.0.6
• FreePBX deployments exposing the Network Scanning feature

Discovery Timeline

• 2025-10-14 - CVE-2025-59051 published to NVD
• 2026-04-15 - Last updated in NVD database

Technical Details for CVE-2025-59051

Vulnerability Analysis

The FreePBX Endpoint Manager module ships a web-based wrapper around the nmap utility to help administrators discover SIP phones and other devices on the local network. The wrapper passes user-controlled parameters into a shell invocation without adequate input neutralization. An authenticated user with access to the Endpoint Manager interface can inject shell metacharacters into the scan parameters, causing the underlying shell to execute additional commands beyond nmap.

Because the FreePBX web stack runs Asterisk-related operations under the asterisk service account, injected commands inherit that account's permissions. The asterisk user typically owns call detail records, voicemail data, dialplan configurations, and recordings. Attackers gain access to sensitive telephony data and can modify call routing, intercept voicemail, or stage further attacks against the host.

Root Cause

The root cause is improper neutralization of special elements supplied to an OS command [CWE-78]. The Network Scanning handler concatenates user-supplied scan targets or options into a shell command string instead of using safe argument arrays or strict allow-list validation. Shell metacharacters such as ;, |, &&, and backticks pass through to the interpreter unchanged.

Attack Vector

The attack is network-reachable through the FreePBX administrative web interface. An attacker authenticates using a known username and valid credentials, then issues a crafted request to the Network Scanning endpoint. The injected payload is appended to the nmap invocation and executed by the shell as the asterisk user. No user interaction beyond the attacker's own session is required.

The vulnerability mechanism is described in the FreePBX GitHub Security Advisory GHSA-qgj3-f9gj-98v9. No public proof-of-concept code is referenced in the advisory.

Detection Methods for CVE-2025-59051

Indicators of Compromise

• Unexpected child processes spawned by the FreePBX web server or PHP-FPM workers running as asterisk, such as /bin/sh, bash, wget, curl, nc, or python invocations following an nmap execution.
• Outbound network connections from the FreePBX host to attacker-controlled infrastructure shortly after Endpoint Manager Network Scanning activity.
• Modifications to Asterisk configuration files (/etc/asterisk/) or addition of new cron entries for the asterisk user.

Detection Strategies

• Inspect web server access logs for POST requests to Endpoint Manager Network Scanning endpoints containing shell metacharacters such as ;, |, `, $(, or URL-encoded equivalents.
• Correlate nmap process executions on FreePBX hosts with subsequent unrelated process spawns under the same parent PID.
• Alert on authenticated administrative actions originating from unusual source IPs or outside normal change windows.

Monitoring Recommendations

• Enable verbose audit logging on the Endpoint Manager module and forward FreePBX logs to a centralized SIEM for retention and correlation.
• Monitor process trees on the FreePBX host using a Linux-capable EDR to flag command chains rooted in the web service account.
• Track integrity of /etc/asterisk/ and PBX module directories to detect post-exploitation persistence.

How to Mitigate CVE-2025-59051

Immediate Actions Required

• Upgrade FreePBX Endpoint Manager to version 16.0.92 or 17.0.6 or later as published by the FreePBX project.
• Rotate credentials for all FreePBX administrative accounts, especially any accounts whose usernames may be known or guessable.
• Restrict access to the FreePBX administrative web interface to trusted management networks using firewall rules or a VPN.

Patch Information

The FreePBX project addresses CVE-2025-59051 in Endpoint Manager 16.0.92 and 17.0.6. Patch details and release notes are available in the FreePBX Security Advisory GHSA-qgj3-f9gj-98v9. Administrators should apply the update through the standard FreePBX module manager and verify the new version after installation.

Workarounds

• Disable the Network Scanning feature within Endpoint Manager until the patched version is installed.
• Enforce strong, unique passwords and multi-factor authentication for all FreePBX administrative accounts to reduce the risk of credential-based exploitation.
• Place the FreePBX administrative interface behind a reverse proxy or VPN that requires additional authentication and source IP restrictions.

# Verify installed Endpoint Manager version and update via FreePBX CLI
fwconsole ma list | grep -i endpoint
fwconsole ma downloadinstall endpoint
fwconsole ma upgrade endpoint
fwconsole reload

# Restrict administrative UI access at the host firewall (example: allow only management subnet)
iptables -A INPUT -p tcp --dport 443 -s 10.10.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP