CVE-2026-77004 in CF-N1-S
Summary
by MITRE • 08/20/2026
A flaw has been found in Comfast CF-N1-S 2.6.0.1. This impacts the function sprintf of the file /cgi-bin/mbox-config?method=SET§ion=ptest_sn. Executing a manipulation of the argument sn can lead to command injection. The attack can be launched remotely. The exploit has been published and may be used.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 08/20/2026
The vulnerability identified in Comfast CF-N1-S firmware version 2.6.0.1 represents a critical security flaw rooted in improper input validation within the device's web management interface. Specifically, the issue resides in the sprintf function located at the CGI endpoint /cgi-bin/mbox-config when invoked with the method parameter set to SET and the section parameter designated as ptest_sn. This configuration path is responsible for handling network diagnostic tests, particularly those involving ping or traceroute operations against a specified target address. The core technical deficiency lies in the failure of the application code to adequately sanitize user-supplied input before passing it to system-level command execution functions. By manipulating the sn argument, which typically expects an IP address or hostname, an attacker can inject malicious shell metacharacters into the command string constructed by the sprintf function.
This flaw directly facilitates a Remote Code Execution (RCE) vulnerability, classified under CWE-78 as Improper Neutralization of Special Elements used in an OS Command. The mechanism allows for arbitrary command injection because the input is concatenated directly into system calls without sufficient filtering or escaping of dangerous characters such as semicolons, pipes, or backticks. Consequently, if a remote attacker sends a crafted HTTP request to this endpoint with specially formatted data in the sn parameter, they can execute operating system commands with the privileges of the web server process, which often runs with elevated permissions on embedded devices like routers and access points. The presence of an available exploit indicates that this vulnerability is well-understood by threat actors and poses a significant risk to deployed infrastructure.
The operational impact of this vulnerability is severe, as it compromises the confidentiality, integrity, and availability of the affected device. Successful exploitation allows attackers to gain full control over the underlying operating system, enabling them to install persistent backdoors, pivot into internal networks, exfiltrate sensitive data such as Wi-Fi credentials or configuration files, or disrupt network services by terminating critical processes. Given that this is an embedded networking device, compromise can lead to broader network segmentation failures and serve as a foothold for lateral movement within the local area network. The remote nature of the attack means no physical access or prior authentication is required, significantly lowering the barrier to entry for malicious actors scanning the internet for vulnerable IoT devices.
Mitigation strategies must prioritize immediate remediation through firmware updates provided by Comfast that address this input validation gap. If an update is not immediately available, network administrators should implement strict firewall rules to restrict access to the management interface of these devices from untrusted networks or block external traffic targeting port 80 and 443 entirely if remote administration is not required. Additionally, deploying intrusion detection systems with signatures capable of identifying command injection payloads in HTTP requests can provide an additional layer of defense. Long-term security improvements should involve adopting secure coding practices that enforce strict allow-listing for input fields expecting IP addresses or hostnames, ensuring that only valid alphanumeric characters and standard punctuation are accepted while rejecting any shell metacharacters outright. This aligns with ATT&CK technique T1059 Command and Scripting Interpreter, highlighting the need to monitor for unauthorized command execution attempts on network infrastructure devices.