CVE-2026-2534: Comfast CF-N1 Firmware RCE Vulnerability

CVE-2026-2534 Overview

A command injection vulnerability has been identified in Comfast CF-N1 V2 firmware version 2.6.0.2. The vulnerability exists in the sub_44AC4C function within the /cgi-bin/mbox-config?method=SET§ion=ptest_bandwidth endpoint. Improper sanitization of the bandwidth argument allows remote attackers to inject and execute arbitrary system commands on the affected device.

Critical Impact

Remote attackers with low-level authentication can exploit this command injection vulnerability to execute arbitrary commands on Comfast CF-N1 routers, potentially leading to full device compromise, network infiltration, and persistent unauthorized access.

Affected Products

• Comfast CF-N1 Firmware version 2.6.0.2
• Comfast CF-N1 Hardware V2

Discovery Timeline

• February 16, 2026 - CVE-2026-2534 published to NVD
• February 19, 2026 - Last updated in NVD database

Technical Details for CVE-2026-2534

Vulnerability Analysis

This vulnerability is classified as a command injection flaw (CWE-77) with an underlying injection weakness (CWE-74). The affected function sub_44AC4C processes user-supplied input from the bandwidth parameter without adequate sanitization or validation. This architectural weakness allows attackers to append malicious shell commands that are then executed with the privileges of the web server process on the embedded device.

The network-accessible nature of this vulnerability means that any authenticated attacker with network access to the router's management interface can potentially exploit this flaw. Embedded router devices like the Comfast CF-N1 typically run with elevated privileges, meaning successful exploitation could grant attackers root-level access to the device.

Root Cause

The root cause stems from insufficient input validation in the sub_44AC4C function when handling the bandwidth parameter. The function appears to directly incorporate user input into system commands without proper sanitization, escaping, or parameterization. This allows metacharacters and command separators (such as ;, |, or &&) to break out of the intended command context and execute attacker-controlled commands.

Attack Vector

The attack is executed remotely over the network by sending a crafted HTTP request to the vulnerable CGI endpoint. An attacker with low-level privileges on the router can manipulate the bandwidth argument in a request to /cgi-bin/mbox-config?method=SET§ion=ptest_bandwidth to inject arbitrary shell commands.

The exploitation flow involves:

1. Authenticating to the router's web management interface
2. Crafting a malicious request to the vulnerable endpoint with injected commands in the bandwidth parameter
3. The device's embedded web server processes the request and passes unsanitized input to the vulnerable function
4. Injected commands execute on the underlying operating system with web server privileges

Technical details and proof-of-concept information are available in the GitHub CVE Analysis repository.

Detection Methods for CVE-2026-2534

Indicators of Compromise

• Unexpected HTTP requests to /cgi-bin/mbox-config endpoint with unusual bandwidth parameter values containing shell metacharacters (;, |, &&, $(, backticks)
• Anomalous process execution on the router such as reverse shells, wget/curl downloads, or reconnaissance commands
• Unauthorized configuration changes or new user accounts on the device
• Network traffic from the router to external command and control servers

Detection Strategies

• Implement network-based intrusion detection rules to monitor for HTTP requests to /cgi-bin/mbox-config containing command injection patterns
• Deploy web application firewall rules to filter requests with shell metacharacters in CGI parameters
• Monitor router logs for failed or suspicious authentication attempts followed by requests to the vulnerable endpoint
• Enable alerting for any outbound connections initiated by the router to unexpected destinations

Monitoring Recommendations

• Regularly audit router access logs for requests to the /cgi-bin/mbox-config endpoint
• Configure network monitoring to detect unusual traffic patterns from IoT and network infrastructure devices
• Implement baseline monitoring for normal router behavior and alert on deviations
• Deploy honeypot configurations to detect active scanning for this vulnerability

How to Mitigate CVE-2026-2534

Immediate Actions Required

• Restrict access to the router's web management interface to trusted IP addresses only
• Disable remote management access if not strictly required
• Place affected devices behind a firewall that blocks external access to the CGI endpoints
• Monitor the vendor's website for firmware updates addressing this vulnerability

Patch Information

The vendor (Comfast) was contacted regarding this vulnerability but did not respond. As of the last update on February 19, 2026, no official patch has been released. Organizations should monitor the VulDB entry and vendor channels for future patch availability.

Workarounds

• Implement network segmentation to isolate affected devices from critical network segments
• Use firewall rules to block access to /cgi-bin/mbox-config from untrusted networks
• Consider replacing affected devices with alternative hardware from vendors with better security response practices
• Deploy a reverse proxy with input validation capabilities in front of the management interface

# Example iptables rules to restrict management access
# Allow management interface access only from trusted admin network
iptables -A INPUT -p tcp --dport 80 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP

# Block access to vulnerable CGI endpoint from external networks
iptables -A INPUT -p tcp --dport 80 -m string --string "/cgi-bin/mbox-config" --algo bm -j DROP