A command injection vulnerability in the CGI program of the Zyxel ARMOR Z1/Z2 firmware could allow an attacker to execute arbitrary OS comm…

published 2022-02-22 4 y ago modified 2026-06-17 4 mo ago also EUVD-2021-33930

cvss: 8.8; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.7%; EPSS 0.7% chance of exploitation in 30 days, percentile 55%
public exploits: 0; none known

A command injection vulnerability in the CGI program of the Zyxel ARMOR Z1/Z2 firmware could allow an attacker to execute arbitrary OS commands via a LAN interface.

Patch / fix

fixed in 1

zyxel nbg6817_firmware 1.00\(abcs.11\)c0

Exploit prediction

0.75% chance of exploitation in the next 30 days, higher than 55% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	8.8	CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD	3.1	8.8	CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD	2.0	8.3	AV:A/AC:L/Au:N/C:C/I:C/A:C

Affected products

Zyxel ARMOR Z2 (NBG6817) firmware
Zyxel ARMOR Z1 (NBG6816) firmware

Classification

Weakness

CWE-78 Improper Neutralization of Special Elements used in an OS Command

References

zyxel.com /support/forgery-vulnerabilities-of-select-Armor-home-routers.shtml
vendor-advisory

Sources

CVE List CVE-2021-4029
NVD CVE-2021-4029

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Summary