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Vulnerability record · CVE-2021-35030 · published 26 July 2021

CVE-2021-35030: Zyxel gs1900-8 firmware cross-site scripting vulnerability

Zyxel · Gs1900 8 Firmware

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.

4.3 CVSS 3.1 Medium EPSS 0.27% · top 82.5% CWE-79 · Cross-site scripting
4.3CVSS 3.1 base score, v2 2.3
0.27%EPSS exploitation probability, 30 days
NoNot in CISA KEV
12Affected product versions listed by NVD
2References
17 Jun 2026Last modified by NVD

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.

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

Affected products

12 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://www.zyxel.com/support/Zyxel_security_advisory_for_XSS_vulnerability_of_GS1900_series_switches.shtml PatchVendor Advisory
https://www.zyxel.com/support/Zyxel_security_advisory_for_XSS_vulnerability_of_GS1900_series_switches.shtml PatchVendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

8.8CVE-2026-7273Zyxel gs1900-8 firmware stack-based buffer overflow vulnerabilityA stack-based buffer overflow vulnerability in the CGI program of Zyxel GS1900-48HPv2 firmware versions through 2.90(ABTQ.1)C0 could allow a LAN-base…KEVEPSS 2.5%9.8CVE-2019-15800Zyxel gs1900-8 firmware os command injection vulnerabilityAn issue was discovered on Zyxel GS1900 devices with firmware before 2.50(AAHH.0)C0. Due to lack of input validation in the cmd_sys_traceroute_exec()…EPSS 3.9%9.8CVE-2016-1329Samsung x14j firmware improper authentication vulnerabilityCisco NX-OS 6.0(2)U6(1) through 6.0(2)U6(5) on Nexus 3000 devices and 6.0(2)A6(1) through 6.0(2)A6(5) and 6.0(2)A7(1) on Nexus 3500 devices has hardc…EPSS 3.7%9.8CVE-2015-5989Zyxel gs1900-10hp firmware permissions and access controls vulnerabilityBelkin F9K1102 2 devices with firmware 2.10.17 rely on client-side JavaScript code for authorization, which allows remote attackers to obtain adminis…EPSS 2.8%9.8CVE-2015-5988Zyxel gs1900-10hp firmware vulnerabilityThe web management interface on Belkin F9K1102 2 devices with firmware 2.10.17 has a blank password, which allows remote attackers to obtain administ…EPSS 2.7%9.1CVE-2019-15803Zyxel gs1900-8 firmware improper authentication vulnerabilityAn issue was discovered on Zyxel GS1900 devices with firmware before 2.50(AAHH.0)C0. Through an undocumented sequence of keypresses, undocumented fun…EPSS 1.3%8.8CVE-2019-15799Zyxel gs1900-8 firmware improper privilege management vulnerabilityAn issue was discovered on Zyxel GS1900 devices with firmware before 2.50(AAHH.0)C0. User accounts created through the web interface of the device, w…EPSS 2.3%8.8CVE-2016-1302Samsung x14j firmware improper access control vulnerabilityCisco Application Policy Infrastructure Controller (APIC) devices with software before 1.0(3h) and 1.1 before 1.1(1j) and Nexus 9000 ACI Mode switche…EPSS 2.2%

Source: NIST National Vulnerability Database (record CVE-2021-35030), CISA KEV, FIRST EPSS (scores of 2026-10-11). This page is refreshed as NVD updates the record.