CVE-2026-4468: Comfast CF-AC100 RCE Vulnerability

CVE-2026-4468 Overview

A command injection vulnerability has been identified in Comfast CF-AC100 firmware version 2.6.0.8. The vulnerability exists in an unknown function of the file /cgi-bin/mbox-config?method=SET§ion=update_interface_png. By manipulating input parameters, an attacker can inject arbitrary commands that are executed on the underlying system. This attack can be carried out remotely over the network, though it requires high privileges to exploit.

Critical Impact

Remote attackers with high privileges can execute arbitrary commands on affected Comfast CF-AC100 devices, potentially leading to complete device compromise, network pivot points, or persistent access to the network infrastructure.

Affected Products

• Comfast CF-AC100 firmware version 2.6.0.8

Discovery Timeline

• 2026-03-20 - CVE CVE-2026-4468 published to NVD
• 2026-03-20 - Last updated in NVD database

Technical Details for CVE-2026-4468

Vulnerability Analysis

This vulnerability is classified under CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component, commonly known as "Injection"). The affected endpoint /cgi-bin/mbox-config with the method=SET and section=update_interface_png parameters fails to properly sanitize user-supplied input before passing it to system command execution functions.

The exploit has been publicly disclosed according to VulDB documentation, increasing the risk of exploitation in the wild. The vendor (Comfast) was contacted early about this disclosure but did not respond, leaving affected devices without an official patch.

Root Cause

The root cause of this vulnerability is improper input validation and sanitization in the CGI handler for the mbox-config endpoint. When processing requests to update interface PNG configurations, user-supplied input is concatenated directly into shell commands without proper escaping or filtering of special characters. This allows attackers to inject shell metacharacters and arbitrary commands.

Attack Vector

The attack is network-based and can be executed remotely against exposed Comfast CF-AC100 devices. An attacker with high-level privileges on the device can craft malicious HTTP requests to the vulnerable CGI endpoint. By including command injection payloads within the request parameters, the attacker can execute arbitrary system commands with the privileges of the web server process.

The vulnerability is accessible via HTTP requests to the /cgi-bin/mbox-config endpoint. The exploitation technique involves manipulating parameters in the method=SET§ion=update_interface_png request to include shell metacharacters that break out of the intended command context. Additional technical details are available in the GitHub CVE Documentation.

Detection Methods for CVE-2026-4468

Indicators of Compromise

• Unusual HTTP requests to /cgi-bin/mbox-config containing shell metacharacters (;, |, $(), backticks)
• Unexpected outbound network connections from the Comfast CF-AC100 device
• Modified configuration files or unauthorized user accounts on the device
• Suspicious process spawning from the web server context

Detection Strategies

• Monitor web server access logs for requests to /cgi-bin/mbox-config?method=SET§ion=update_interface_png with unusual parameter values
• Implement intrusion detection rules to flag HTTP requests containing common command injection patterns targeting this endpoint
• Deploy network-based anomaly detection to identify unexpected traffic patterns from router/access point devices

Monitoring Recommendations

• Enable comprehensive logging on network infrastructure devices including the CF-AC100
• Configure SIEM alerts for command injection attack patterns in HTTP traffic destined for IoT/network devices
• Periodically audit device configurations and compare against known-good baselines
• Monitor for firmware integrity changes on affected devices

How to Mitigate CVE-2026-4468

Immediate Actions Required

• Restrict network access to the web management interface of affected CF-AC100 devices using firewall rules or VLANs
• Disable remote management if not required, limiting access to local/trusted networks only
• Implement strong authentication and limit the number of privileged accounts
• Consider replacing vulnerable devices with alternatives from vendors with better security response practices

Patch Information

No official patch is currently available from Comfast. According to the vulnerability disclosure, the vendor was contacted early about this issue but did not respond. Users should monitor for firmware updates from Comfast and apply them immediately when available.

For the latest information on this vulnerability, refer to the VulDB entry or the GitHub CVE documentation.

Workarounds

• Place the CF-AC100 management interface behind a VPN or on an isolated management network
• Implement web application firewall (WAF) rules to filter requests containing command injection payloads
• Use network segmentation to limit the blast radius if a device is compromised
• Disable the vulnerable CGI functionality if possible without impacting required features

# Example: Restrict access to management interface using iptables on an upstream device
iptables -A FORWARD -d <CF-AC100-IP> -p tcp --dport 80 -j DROP
iptables -A FORWARD -d <CF-AC100-IP> -p tcp --dport 443 -j DROP
# Allow only from trusted management subnet
iptables -I FORWARD -s 192.168.100.0/24 -d <CF-AC100-IP> -p tcp --dport 80 -j ACCEPT