---
id: CVE-2026-71931
title: >-
  Multiple DrayTek VigorSwitch models contain a command injection vulnerability
  in the tftp_upgrade function
summary: >-
  Multiple DrayTek VigorSwitch models contain a command injection vulnerability
  in the tftp_upgrade function. The vulnerability is caused by insufficient
  filtering before the filename field is concatenated into a command. A remote
  attacker…
severity: high
cvss: 7.2
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-78
published: '2026-08-24'
updated: '2026-10-12'
sourceUpdated: '2026-10-12T22:10:00.247'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-71931'
references:
  - url: >-
      https://www.draytek.com/about/security-advisory/multiple-vulnerabilities-in-vigorswitch-series-august-2026/
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/draytek-vigorswitch-multiple-models-os-command-injection-via-tftp-upgrade
    label: disclosure@vulncheck.com
tags:
  - nvd
epss: 0.01783
epssPercentile: 0.77681
ingestedAt: '2026-10-12T23:07:25.623Z'
---

## Overview

Multiple DrayTek VigorSwitch models contain a command injection vulnerability in the tftp_upgrade function. The vulnerability is caused by insufficient filtering before the filename field is concatenated into a command. A remote attacker can trigger this vulnerability via crafted input to execute arbitrary commands with root privileges. Exploitation requires valid administrative credentials for the device's web management interface.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.