Comfast CF-N1-S Router Stack-Based Buffer Overflow (CVE-2026-94003)

Technical Analysis

The vulnerability resides in /cgi-bin/mbox-config, where the get_css_path_from_uri function fails to properly bound-check input before copying it into a fixed-size stack buffer, resulting in a classic stack-based buffer overflow. Because the flaw is reachable via the web management interface without authentication and can be triggered remotely, attackers can craft malicious HTTP requests to overwrite return addresses and achieve arbitrary code execution on the device. Public disclosure of the exploit significantly raises the risk of mass scanning and exploitation, particularly given routers are frequently internet-facing and poorly patched. Organizations deploying AI agents or automation tools behind or through compromised Comfast routers face risk of network-level man-in-the-middle attacks, DNS hijacking, or traffic interception that could expose API keys, credentials, or exfiltrate data used by agentic workflows traversing the compromised network.

Affected Systems

Comfast CF-N1-S router firmware version 2.6.0.1, Web Management Interface component, /cgi-bin/mbox-config endpoint

Indicators of Compromise

• No specific IOCs (hashes, IPs, domains) provided in source data; exploit relies on crafted HTTP requests targeting /cgi-bin/mbox-config parameter used by get_css_path_from_uri

Remediation Steps

1. 1

   Isolate affected devices

   Immediately restrict remote/internet access to the router's web management interface; disable WAN-side management if enabled.

2. 2

   Apply vendor patch

   Monitor Comfast's official channels for a firmware update addressing this vulnerability and apply as soon as available.

3. 3

   Network segmentation

   Place affected devices behind a firewall or VLAN separate from critical infrastructure and AI agent/automation systems to limit lateral movement.

4. 4

   Monitor for exploitation attempts

   Deploy IDS/IPS signatures to detect anomalous requests to /cgi-bin/mbox-config and unusual traffic patterns indicative of buffer overflow attempts.

5. 5

   Replace unsupported hardware

   If no patch is released, consider replacing the device with a supported, actively maintained router model.