CVE-2026-78050 in CF-N1-S
Summary
by MITRE • 08/23/2026
A vulnerability was found in Comfast CF-N1-S 2.6.0.1. The affected element is the function sub_41AD7C of the file /cgi-bin/mbox-config?method=SET§ion=ntp_timezone of the component Web Management. The manipulation of the argument timestr/ntp_client_enabled results in stack-based buffer overflow. It is possible to launch the attack remotely. The exploit has been made public and could be used.
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Analysis
by VulDB Data Team • 08/23/2026
The vulnerability identified within the Comfast CF-N1-S router running firmware version 2.6.0.1 represents a critical security flaw located in the Web Management component, specifically affecting the CGI script endpoint /cgi-bin/mbox-config when invoked with the method SET and section ntp_timezone parameters. This issue is technically rooted in the function sub_41AD7C, which handles the processing of input arguments related to time synchronization settings. The core technical flaw is a stack-based buffer overflow caused by improper validation or bounds checking of the timestr and ntp_client_enabled arguments provided by the user. When an attacker supplies crafted data that exceeds the allocated memory space on the call stack, it overwrites adjacent memory locations, potentially allowing for arbitrary code execution with the privileges of the compromised process.
From a threat modeling perspective, this vulnerability is classified under CWE-121, which denotes a stack-based buffer overflow. This type of flaw is particularly dangerous because it can lead to complete system compromise if exploited successfully. The operational impact is severe due to the remote nature of the attack vector. Since the vulnerable function is accessible via an HTTP endpoint within the web management interface, an attacker does not need physical access or prior authentication credentials in many default configurations, although some routers may require login for certain settings pages. However, given that NTP configuration changes are often permitted without strict privilege escalation checks in older firmware versions, this attack can be launched remotely over a network connection. The availability of public exploits significantly lowers the barrier to entry for malicious actors, increasing the likelihood of automated attacks targeting devices with known vulnerable signatures.
The exploitation of this vulnerability typically involves sending a specially crafted HTTP POST request containing an oversized payload within the timestr or ntp_client_enabled fields. Upon processing by sub_41AD7C, the overflow allows the attacker to overwrite critical stack memory structures such as return addresses or function pointers. This manipulation can redirect program execution flow to shellcode injected into the buffer, granting the attacker a remote command shell on the device. Once control is established, the compromised router can be used for various malicious activities including pivoting into internal networks, launching distributed denial-of-service attacks, intercepting traffic through man-in-the-middle techniques, or installing persistent malware such as botnet agents like Mirai variants which frequently target IoT devices with similar vulnerabilities.
To mitigate this risk, immediate action is required to update the firmware on all affected Comfast CF-N1-S units to a patched version where sub_41AD7C has been hardened against buffer overflows through proper input sanitization and length checks. If an official patch is unavailable or cannot be applied immediately, network-level controls should be implemented to restrict access to the web management interface from untrusted networks. This can be achieved by placing the router behind a firewall that blocks external HTTP/HTTPS traffic destined for port 80 or 443 associated with the device's administrative ports. Additionally, disabling remote management features entirely is recommended as a best practice for home and small office routers to reduce the attack surface exposed to the internet. Security monitoring tools should also be configured to detect anomalous POST requests containing unusually large payloads directed at CGI endpoints on internal network segments.