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Fencer Intel
medium 6.8

CVE-2021-35031 json

A vulnerability in the TFTP client of Zyxel GS1900 series firmware, XGS1210 series firmware, and XGS1250 series firmware, which could allow…

published 4y ago modified 4mo ago also EUVD-2021-21678

cvss
6.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 41%
public exploits
0
none known

Summary

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.

Patch / fix

  • 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

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Exploit prediction

0.48% chance of exploitation in the next 30 days, higher than 41% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 6.8 CVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 8.0 CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.7 AV:A/AC:L/Au:S/C:C/I:C/A:C

Affected products

  • Zyxel GS1900 series firmware
  • Zyxel XGS1210 series firmware
  • Zyxel XGS1250 series firmware

Classification

Weakness
  • CWE-78 Improper Neutralization of Special Elements used in an OS Command

References

Sources

Fencer Intel 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.