What is CVE-2026-77683?

CVE-2026-77683 is a critical-severity vulnerability in Comfast Cf-N1-S, classified under Improper Neutralization of Special Elements in Output Used by a Downstream Component (Injection). CVSS score: 9.9/10. Published 2026-08-21.

How severe is CVE-2026-77683?

Critical severity. CVSS v3 base score is 9.9 out of 10.

RCE in Comfast Cf-N1-S

CVE-2026-77683

A security flaw has been discovered in Comfast CF-N1-S 2.6.0.1. Affected by this issue is the function system of the file /cgi-bin/mbox-config?method=SET&section=ntp_timezone. The manipulation of the argument timestr results in command injection. The attack can be launched remotely. The exploit has been released to the public and may be used for attacks.

Published 2026-08-21 · last modified 2026-08-24.

CVSS v3 metric

CVSS v3 base score 9.9 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.029 (86.4th percentile), scored 2026-10-06.

Low probability of exploitation in the next 30 days, but still tracked. 86th percentile — 86.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.015 · newest: 0.029 · change: +0.014

Affected products

Comfast Cf-N1-S — versions 2.6.0.1

Weakness classification (CWE)

References

vuldb.com/vuln/394033 (technical-description, vdb-entry)
vuldb.com/vuln/394033/cti (signature, permissions-required)
vuldb.com/cve/CVE-2026-77683 (third-party-advisory)
vuldb.com/submit/881058 (third-party-advisory)
github.com/AdminSafe/CVE/issues/8 (issue-tracking, exploit)

Frequently asked questions

What is CVE-2026-77683?: CVE-2026-77683 is a critical-severity vulnerability in Comfast Cf-N1-S, classified under Improper Neutralization of Special Elements in Output Used by a Downstream Component (Injection). CVSS score: 9.9/10. Published 2026-08-21.
How severe is CVE-2026-77683?: Critical severity. CVSS v3 base score is 9.9 out of 10.