CVE-2026-94003: Comfast CF-N1-S Buffer Overflow

How to Detect CVE-2026-94003

Start by identifying all Comfast CF-N1-S devices and recording their firmware versions. Check Internet-facing asset inventories, firewall NAT rules, remote administration settings, and vulnerability-scanning results. A device running version 2.6.0.1 should be treated as vulnerable even if no suspicious activity has been observed.

Review web server, reverse-proxy, firewall, and network telemetry for requests to /cgi-bin/mbox-config. Because the exact vulnerable parameter and request format are unknown, detection should focus on the endpoint and anomalous request characteristics rather than a narrow signature.

Look for:

• Unusually long request targets
• Encoded or malformed input
• Repeated HTTP 4xx or 5xx responses
• Unexpected HTTP 500 responses
• Device reboots
• Management-service restarts
• Connection loss following suspicious requests
• Repeated requests from the same external source

Log Search Example

A generic Linux or SIEM-oriented search for endpoint access may begin with:

grep -Ei '(/cgi-bin/mbox-config|get_css_path_from_uri)' \
  /var/log/nginx/access.log \
  /var/log/apache2/access.log \
  /var/log/httpd/access_log

For JSON-formatted web logs in a tool such as jq, use an endpoint-focused query such as:

jq -r '
  select(
    (.uri? // .request_uri? // "") | test("^/cgi-bin/mbox-config")
  )
  | [.timestamp, .src_ip, .method, (.uri // .request_uri), .status]
  | @tsv
' access.json

A practical detection pattern could alert on combinations such as:

request_uri starts with /cgi-bin/mbox-config
AND (request length is unusually large OR repeated 4xx/5xx responses)
AND (device reboot, management process restart, or connection loss follows)

These queries are illustrative and must be adapted to the device’s actual logging location and format. The Comfast device may not retain detailed HTTP logs locally, so upstream firewall, proxy, or network sensor logging may be required.

Mitigation and Patching

No vendor-confirmed fixed firmware version was identified in the available record. The immediate mitigation is to remove the Web Management Interface from Internet exposure and restrict access to a trusted administration network. Use a VPN or dedicated management VLAN where possible, and block unsolicited WAN-to-management traffic at the perimeter.

Contact Comfast support or consult its official firmware download channel for a security update specifically addressing CVE-2026-94003 and CF-N1-S firmware 2.6.0.1. Do not treat an unrelated later release as a confirmed fix. If Comfast cannot provide supported remediation within the organization’s risk window, replacement is the safer option, particularly for devices operating at the network perimeter.

Organizations should also:

1. Disable remote administration from the WAN if the feature is enabled.
2. Restrict management access to a VPN or administrative jump host.
3. Preserve device configuration and logs before firmware changes.
4. Confirm the hardware model and installed version after any upgrade.
5. Monitor for reboots, management-service failures, and unusual requests to /cgi-bin/mbox-config.
6. Rotate administrative passwords if compromise is suspected.
7. Replace the device if no supported fixed firmware is available.

When rotating administrative credentials, store unique passwords in an approved password manager such as Try 1Password → rather than reusing credentials across network devices.

Example Firewall Controls

A Linux firewall can block inbound access to a management address or port. The exact port and interface depend on the deployment, so substitute the device’s actual management port and address:

sudo iptables -A INPUT -p tcp -s 192.0.2.0/24 -d 192.0.2.10 \
  --dport 80 -j ACCEPT

sudo iptables -A INPUT -p tcp -d 192.0.2.10 \
  --dport 80 -j DROP

The first rule permits management only from the trusted administration subnet; the second blocks other sources. Apply equivalent controls on the upstream firewall or router because a host-level rule may not be available on the embedded device. Validate the result from both an approved management host and an untrusted network.

Incident Response Considerations

If a vulnerable device was exposed to the Internet, preserve relevant firewall, proxy, and network logs before making changes. Record the device’s firmware version, configuration, uptime, reboot history, and known administrative users.

Investigate:

• Requests to /cgi-bin/mbox-config
• Unexpected configuration changes
• New administrator accounts
• DNS or routing changes
• Unusual outbound connections
• Repeated crashes or reboots
• Management access from unfamiliar addresses
• Firmware changes that were not approved

If compromise cannot be ruled out, isolate the device, preserve evidence, reset credentials from a trusted system, and replace or reflash the device using an official vendor image where available. A factory reset alone may not address a firmware-level compromise or an underlying vulnerability.

References

The primary reference is the NVD record for CVE-2026-94003, which identifies the Comfast CF-N1-S, firmware 2.6.0.1, the affected file and function, remote attack capability, CVSS score of 10.0, and public disclosure status.

Additional references include the publicly referenced GitHub issue and VulDB records. These sources should be used as leads for further validation, not as substitutes for vendor confirmation of affected ranges or remediation status.

• NVD: CVE-2026-94003
• GitHub: AdminSafe/CVE issue #12
• VulDB: CVE-2026-94003
• VulDB vulnerability record
• VulDB CTI record

As of 2026-09-20, no confirmed fixed version, complete CVSS vector, independently validated working PoC, or confirmed in-the-wild exploitation was identified in the available research.

This article may contain affiliate links. We earn a commission on qualifying purchases at no extra cost to you.