What is CVE-2021-35031?

CVE-2021-35031 is a medium-severity vulnerability in Zyxel Gs1900-10hp, classified under OS Command Injection. CVSS score: 6.8/10. Published 2021-12-28.

How severe is CVE-2021-35031?

Medium severity. CVSS v3 base score is 6.8 out of 10.

RCE in Zyxel Gs1900-10hp

CVE-2021-35031

A vulnerability in the TFTP client of Zyxel GS1900 series firmware, XGS1210 series firmware, and XGS1250 series firmware, which could allow an authenticated LAN user to execute arbitrary OS commands via the GUI of the vulnerable device.

Vulnerability class: Command Injection (OS Command Injection)

Published 2021-12-28 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.8 (Medium). Vector: CVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.005 (40.3th percentile), scored 2026-10-23.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 40th percentile — 40.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: +0.000

Affected products

Weakness classification (CWE)

CWE-78 — OS Command Injection

References

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

Frequently asked questions

What is CVE-2021-35031?: CVE-2021-35031 is a medium-severity vulnerability in Zyxel Gs1900-10hp, classified under OS Command Injection. CVSS score: 6.8/10. Published 2021-12-28.
How severe is CVE-2021-35031?: Medium severity. CVSS v3 base score is 6.8 out of 10.