CVE-2021-35031

Name: CVE-2021-35031
Creator: NVD / NIST
Published: 2021-12-28T11:15:07.463+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 8/10EPSS 0.46%

Last modified Jun 17, 2026

CVE-2021-35031 is a high-severity vulnerability rated 8/10 on the CVSS scale. 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.. EPSS estimates a 0.46% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1

8/10

CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

0.46%

36.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Zyxel	Gs1900-8 Firmware	< 2.70\(aahh.0\)-20211208
Zyxel	Gs1900-8hp Firmware	< 2.70\(aahi.0\)-20211208
Zyxel	Gs1900-10hp Firmware	< 2.70\(aazi.0\)-20211208
Zyxel	Gs1900-16 Firmware	< 2.70\(aahj.0\)-20211208
Zyxel	Gs1900-24e Firmware	< 2.70\(aahk.0\)-20211208
Zyxel	Gs1900-24ep Firmware	< 2.70\(abto.0\)-20211208
Zyxel	Gs1900-24 Firmware	< 2.70\(aahl.0\)-20211208
Zyxel	Gs1900-24hp Firmware	< 2.70\(aahm.0\)-20211208
Zyxel	Gs1900-24hpv2 Firmware	< 2.70\(aatp.0\)-20211208
Zyxel	Gs1900-48 Firmware	< 2.70\(aahn.0\)-20211208
Zyxel	Gs1900-48hp Firmware	< 2.70\(aaho.0\)-20211208
Zyxel	Gs1900-48hpv2 Firmware	< 2.70\(abtq.0\)-20211208
Zyxel	Xgs1210-12 Firmware	< 1.00\(abty.5\)c0
Zyxel	Xgs1250-12 Firmware	< 1.00\(abwe.1\)c0

References

https://www.zyxel.com/support/Zyxel_security_advisory_for_OS_command_injection_vulnerabilities_of_switches.shtmlPatch, Vendor Advisory
https://www.zyxel.com/support/Zyxel_security_advisory_for_OS_command_injection_vulnerabilities_of_switches.shtmlPatch, Vendor Advisory

Timeline

Published: Dec 28, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-35031?

How severe is CVE-2021-35031?

CVE-2021-35031 has a CVSS score of 8/10 (HIGH severity). The EPSS model estimates a 0.46% probability of exploitation in the next 30 days.

How do I fix CVE-2021-35031?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-35031?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST