What is CVE-2021-35028?

CVE-2021-35028 is a high-severity vulnerability in Zyxel Zywall Vpn2s, classified under OS Command Injection. CVSS score: 7.3/10. Published 2021-09-29.

How severe is CVE-2021-35028?

High severity. CVSS v3 base score is 7.3 out of 10.

RCE in Zyxel Zywall Vpn2s

CVE-2021-35028

A command injection vulnerability in the CGI program of the Zyxel VPN2S firmware version 1.12 could allow an authenticated, local user to execute arbitrary OS commands.

Vulnerability class: Command Injection (OS Command Injection)

Published 2021-09-29 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.3 (High). Vector: CVSS:3.1/AV:A/AC:H/PR:H/UI:R/S:C/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.003 (20.9th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 21st percentile — 20.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000

Affected products

Zyxel Zywall Vpn2s
Zyxel Zywall Vpn2s Firmware — versions 1.12(ABLN.0)C0
Zyxel Zywall Vpn2s Firmware — versions 1.12(abln.0)c0, 1.12\(abln.0\)c0

Weakness classification (CWE)

CWE-78 — OS Command Injection

References

www.zyxel.com/support/Zyxel_security_advisory_for_directory_traversal_and_comma… (Patch, Vendor Advisory)

Frequently asked questions

What is CVE-2021-35028?: CVE-2021-35028 is a high-severity vulnerability in Zyxel Zywall Vpn2s, classified under OS Command Injection. CVSS score: 7.3/10. Published 2021-09-29.
How severe is CVE-2021-35028?: High severity. CVSS v3 base score is 7.3 out of 10.