CVE-2026-75094: COMFAST CF-N1-S RCE Vulnerability

CVE-2026-75094 Overview

CVE-2026-75094 is an operating system command injection vulnerability [CWE-77] affecting COMFAST CF-N1-S firmware version 2.6.0.1. The flaw resides in the sub_44B438 function processing requests to /cgi-bin/mbox-config?method=SET§ion=ptest_ssid within the CGI Interface component. Attackers manipulate the ssid argument to inject arbitrary operating system commands. Remote exploitation is possible over the network, and a public exploit has been published.

Critical Impact
Remote attackers with valid high-privilege credentials can inject arbitrary operating system commands through the ssid parameter, leading to full compromise of the wireless device.

Affected Products

COMFAST CF-N1-S firmware version 2.6.0.1
CGI Interface component (/cgi-bin/mbox-config handler)
Function sub_44B438 handling the ptest_ssid section

Discovery Timeline

2026-08-18 - CVE-2026-75094 published to NVD
2026-08-20 - Last updated in NVD database

Technical Details for CVE-2026-75094

Vulnerability Analysis

The COMFAST CF-N1-S wireless device exposes a CGI endpoint at /cgi-bin/mbox-config that accepts configuration operations through the method and section query parameters. When method=SET and section=ptest_ssid are supplied, the request is dispatched to the internal handler sub_44B438. This handler consumes the attacker-supplied ssid value and passes it into an operating system command without adequate sanitization or argument separation.

Because the parameter flows into a shell invocation, metacharacters such as backticks, semicolons, and command substitution operators break out of the intended context. The injected commands execute with the privileges of the CGI process, which on embedded routers typically runs as root. Exploitation grants control over the wireless configuration, network traffic, and any services running on the device.

According to EPSS data from 2026-08-23, the vulnerability sits in the upper percentile range for near-term exploitation likelihood, and the vendor advisory notes that a working exploit has been published.

Root Cause

The root cause is improper neutralization of special elements used in an OS command [CWE-77]. The sub_44B438 function concatenates the ssid HTTP parameter directly into a shell command string. No allowlist validation, quoting, or use of execve-style APIs isolates the argument from the command interpreter.

Attack Vector

Exploitation occurs remotely over HTTP against the device management interface. An authenticated attacker submits a crafted GET request to /cgi-bin/mbox-config?method=SET§ion=ptest_ssid with an ssid value containing shell metacharacters and an appended command. The CGI handler evaluates the injected payload and returns control of the underlying operating system to the attacker.

The vulnerability manifests when the attacker-controlled ssid parameter reaches the command interpreter. See the VulDB entry for CVE-2026-75094 and the associated proof-of-concept repository for technical reproduction details.

Detection Methods for CVE-2026-75094

Indicators of Compromise

HTTP requests to /cgi-bin/mbox-config containing method=SET§ion=ptest_ssid with shell metacharacters such as ;, |, &&, `, or $() in the ssid parameter.
Unexpected child processes spawned from the CGI worker on the device, particularly sh, busybox, wget, curl, or tftp.
Outbound connections from the router management plane to unknown hosts shortly after configuration API activity.

Detection Strategies

Inspect web server and CGI access logs for requests targeting mbox-config with non-alphanumeric characters in ssid.
Deploy network intrusion detection signatures matching URI patterns section=ptest_ssid combined with URL-encoded shell operators (%3B, %7C, %60).
Correlate authentication events with configuration API calls to identify compromised administrator accounts abusing the endpoint.

Monitoring Recommendations

Forward device syslog, HTTP access, and process telemetry to a central data lake for retention and anomaly analysis.
Alert on new persistent processes, cron entries, or firewall rule changes on affected COMFAST devices.
Track egress traffic from management VLANs to detect post-exploitation callbacks or tooling downloads.

How to Mitigate CVE-2026-75094

Immediate Actions Required

Restrict access to the device management interface to trusted administrative networks using firewall access control lists.
Rotate all administrator credentials for COMFAST CF-N1-S devices, since exploitation requires authenticated access.
Disable remote WAN-side administration on affected devices until a fixed firmware release is available.
Audit configuration and running processes on any device that has exposed the CGI interface to untrusted networks.

Patch Information

At the time of publication, no vendor patch has been referenced in the NVD entry for CVE-2026-75094. Administrators should monitor the VulDB advisory and COMFAST vendor channels for firmware updates addressing the sub_44B438 handler in the CGI Interface.

Workarounds

Place affected devices behind a segmented management network reachable only via VPN or jump host.
Block external HTTP and HTTPS access to /cgi-bin/mbox-config at an upstream firewall or reverse proxy.
Where feasible, replace the affected model with a supported device that receives active firmware maintenance.

bash

# Example upstream firewall rule to block external access to the vulnerable endpoint
iptables -I FORWARD -p tcp --dport 80 -d <device_ip> \
  -m string --string "/cgi-bin/mbox-config" --algo bm -j DROP
iptables -I FORWARD -p tcp --dport 443 -d <device_ip> \
  -m string --string "/cgi-bin/mbox-config" --algo bm -j DROP