CVE-2021-35030

Name: CVE-2021-35030
Creator: NVD / NIST
Published: 2021-07-26T12:15:08.817+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 4.3/10EPSS 0.27%

Last modified Jun 17, 2026

CVE-2021-35030 is a medium-severity vulnerability rated 4.3/10 on the CVSS scale. A vulnerability was found in the CGI program in Zyxel GS1900-8 firmware version V2.60, that did not properly sterilize packet contents and could allow an authenticated, local user to perform a cross-site scripting (XSS) attack via a crafted LLDP packet.. EPSS estimates a 0.27% chance of exploitation in the next 30 days.

Description

A vulnerability was found in the CGI program in Zyxel GS1900-8 firmware version V2.60, that did not properly sterilize packet contents and could allow an authenticated, local user to perform a cross-site scripting (XSS) attack via a crafted LLDP packet.

Metrics

CVSS 3.1

4.3/10

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

EPSS Probability

0.27%

18.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Zyxel	Gs1900-8 Firmware	< 2.70
Zyxel	Gs1900-8hp Firmware	< 2.70
Zyxel	Gs1900-10hp Firmware	< 2.70
Zyxel	Gs1900-16 Firmware	< 2.70
Zyxel	Gs1900-24e Firmware	< 2.70
Zyxel	Gs1900-24ep Firmware	< 2.70
Zyxel	Gs1900-24 Firmware	< 2.70
Zyxel	Gs1900-24hp Firmware	< 2.70
Zyxel	Gs1900-24hpv2 Firmware	< 2.70
Zyxel	Gs1900-48 Firmware	< 2.70
Zyxel	Gs1900-48hp Firmware	< 2.70
Zyxel	Gs1900-48hpv2 Firmware	< 2.70

References

https://www.zyxel.com/support/Zyxel_security_advisory_for_XSS_vulnerability_of_GS1900_series_switches.shtmlPatch, Vendor Advisory
https://www.zyxel.com/support/Zyxel_security_advisory_for_XSS_vulnerability_of_GS1900_series_switches.shtmlPatch, Vendor Advisory

Timeline

Published: Jul 26, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-35030?

How severe is CVE-2021-35030?

CVE-2021-35030 has a CVSS score of 4.3/10 (MEDIUM severity). The EPSS model estimates a 0.27% probability of exploitation in the next 30 days.

How do I fix CVE-2021-35030?

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-2021-35030?

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

Scan your code now

Source: NVD / NIST