CVE-2026-78050: Comfast CF-N1-S Buffer Overflow Vulnerability

CVE-2026-78050 Overview

CVE-2026-78050 is a stack-based buffer overflow vulnerability in the Comfast CF-N1-S wireless device running firmware version 2.6.0.1. The flaw resides in the sub_41AD7C function processing requests to /cgi-bin/mbox-config?method=SET§ion=ntp_timezone within the Web Management component. Attackers manipulate the timestr and ntp_client_enabled arguments to trigger memory corruption on the stack. The issue is exploitable remotely over the network, and public exploit details are available. The vulnerability is classified under CWE-119 for improper restriction of operations within memory buffer bounds.

Critical Impact
Remote attackers with low privileges can corrupt stack memory in the Comfast CF-N1-S web interface, potentially leading to arbitrary code execution or device compromise.

Affected Products

Comfast CF-N1-S firmware version 2.6.0.1
Web Management component (/cgi-bin/mbox-config endpoint)
sub_41AD7C function within the NTP timezone handler

Discovery Timeline

2026-08-23 - CVE-2026-78050 published to the National Vulnerability Database
2026-08-24 - Last updated in NVD database

Technical Details for CVE-2026-78050

Vulnerability Analysis

The flaw is a stack-based buffer overflow triggered through the CGI endpoint /cgi-bin/mbox-config when handling method=SET§ion=ntp_timezone requests. The sub_41AD7C function reads the user-supplied timestr and ntp_client_enabled parameters without enforcing length checks before copying data into a fixed-size stack buffer. An authenticated remote attacker can send an oversized value to overwrite adjacent stack memory, including the saved return address on MIPS or ARM embedded architectures typical of Comfast hardware. Successful exploitation compromises the confidentiality, integrity, and availability of the device and can pivot to attached network segments.

Root Cause

The root cause is missing input validation in sub_41AD7C. The function accepts attacker-controlled query string values and passes them to an unbounded memory copy routine such as strcpy or sprintf. Because the CGI handler runs with elevated privileges on the embedded Linux system, memory corruption directly translates into device-level compromise. This class of defect maps to CWE-119.

Attack Vector

Exploitation requires network access to the Comfast web management interface and low-level authentication. An attacker crafts an HTTP request targeting /cgi-bin/mbox-config?method=SET§ion=ntp_timezone with an overlong timestr or ntp_client_enabled payload. The oversized string overwrites the stack frame of sub_41AD7C, redirecting execution flow. Public disclosure of the exploit details is referenced in the GitHub issue tracker and VulDB vulnerability record.

No verified proof-of-concept code is included here. Refer to the linked technical references for reproduction details.

Detection Methods for CVE-2026-78050

Indicators of Compromise

HTTP requests to /cgi-bin/mbox-config containing abnormally long timestr or ntp_client_enabled parameters
Unexpected reboots, service crashes, or watchdog resets on Comfast CF-N1-S devices
Outbound connections from the device to unfamiliar hosts following NTP configuration changes

Detection Strategies

Inspect web server and CGI access logs for requests matching the method=SET§ion=ntp_timezone pattern with parameter values exceeding expected lengths
Deploy network intrusion detection signatures that flag long query string arguments targeting Comfast management endpoints
Correlate device crash telemetry with inbound HTTP requests to identify probing or exploitation attempts

Monitoring Recommendations

Restrict management-plane traffic to a dedicated administrative VLAN and monitor for anomalous access from user segments
Alert on repeated 5xx responses from the CGI interface, which may indicate exploitation attempts causing service failures
Baseline normal NTP configuration change frequency and investigate deviations

How to Mitigate CVE-2026-78050

Immediate Actions Required

Block external access to the Comfast web management interface at the perimeter firewall
Change default administrative credentials and enforce strong password policies to raise the bar for the required low-privilege access
Isolate affected CF-N1-S devices on a segmented management network until a vendor patch is available

Patch Information

No vendor patch has been published in the referenced advisories at the time of NVD publication. Monitor the VulDB record for CVE-2026-78050 and Comfast vendor channels for firmware updates addressing the sub_41AD7C boundary check.

Workarounds

Disable remote WAN-side access to the CGI web management interface
Apply access control lists restricting /cgi-bin/mbox-config requests to trusted administrative IP addresses
Consider replacing the device if firmware updates are not forthcoming and exposure cannot be mitigated through network controls

bash

# Example iptables rule restricting management interface access
iptables -A INPUT -p tcp --dport 80 -s 192.168.10.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP