Skip to content
Fencer Vulns
low 3.5

CVE-2021-35030 json

A vulnerability was found in the CGI program in Zyxel GS1900-8 firmware version V2.60, that did not properly sterilize packet contents and…

published 2021-07-26 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-21677

cvss
3.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 19%
public exploits
0
none known

Summary

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.

Patch / fix

  • 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

Exploit prediction

0.27% chance of exploitation in the next 30 days, higher than 19% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 3.5 CVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:L
NVD 3.1 4.3 CVSS:3.1/AV:A/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N
NVD 2.0 2.3 AV:A/AC:M/Au:S/C:N/I:P/A:N

Affected products

  • Zyxel GS1900-8 Firmware

Classification

Weakness
  • CWE-79 Improper Neutralization of Input During Web Page Generation

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.