Comfast CF-N1-S Stack-Based Buffer Overflow (CVE-2026-78050)

Technical Analysis

The vulnerability resides in the sub_41AD7C function handling the /cgi-bin/mbox-config?method=SET&section=ntp_timezone endpoint, where the timestr and ntp_client_enabled parameters are insufficiently validated before being copied into a fixed-size stack buffer, resulting in a stack-based buffer overflow. Because the request is processed by the device's Web Management CGI interface without requiring complex authentication bypass in many deployments, remote attackers can trigger the overflow to corrupt return addresses and potentially achieve arbitrary code execution or persistent denial of service on the router. The CVSS score of 9.9 reflects the low attack complexity, remote network vector, and high impact on confidentiality, integrity, and availability. Organizations using these routers as network infrastructure for edge devices, IoT gateways, or as part of remote access paths for AI agent deployments should treat this as a priority patch, since a compromised router sitting on the network path of an AI agent or RAG pipeline could enable traffic interception, DNS manipulation, or man-in-the-middle attacks against API calls and credential exchanges used by agentic systems.

Affected Systems

Comfast CF-N1-S wireless router firmware version 2.6.0.1, specifically the Web Management component's CGI script handling NTP timezone configuration (mbox-config endpoint)

Indicators of Compromise

• /cgi-bin/mbox-config?method=SET&section=ntp_timezone
• Malformed timestr parameter values exceeding expected buffer length
• Anomalous POST/GET requests to mbox-config CGI endpoint with oversized ntp_client_enabled or timestr fields

Remediation Steps

1. 1

   Apply vendor firmware update

   Check Comfast's official support channels for a patched firmware release addressing this buffer overflow and update all affected CF-N1-S devices immediately.

2. 2

   Restrict Web Management access

   Disable remote/WAN-facing access to the router's Web Management interface and restrict it to trusted LAN IP addresses only, ideally via firewall ACLs or VLAN segmentation.

3. 3

   Deploy network monitoring for exploit patterns

   Implement IDS/IPS signatures to detect and block requests to the mbox-config CGI endpoint containing abnormally long timestr or ntp_client_enabled values.

4. 4

   Isolate vulnerable devices

   If no patch is available, remove the device from production networks or place it behind a hardened gateway until remediation is possible, especially in environments hosting AI agent infrastructure.

5. 5

   Audit network path for AI agent traffic

   Review whether affected routers sit on the network path of AI agent, LLM tool-use, or RAG pipeline traffic, and rotate any credentials or API keys that may have transited compromised infrastructure.