---
id: "CVE-2021-20123"
kind: "vulnerability"
aliases: ["CVE-2021-20123"]
title: "A local file inclusion vulnerability exists in Draytek VigorConnect 1.6.0-B3 in the file download functionality of\u2026"
severity: "critical"
cvss: 7.8
epss: null
exploited: true
status: "open"
category: "infrastructure"
products: [{"name": "DrayTek VigorConnect", "fixed": [], "affected": "", "ecosystem": "vendor"}, {"name": "draytek vigorconnect", "fixed": [], "affected": "= 1.6.0", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["draytek", "exploited", "infrastructure", "self-hosted", "vigorconnect"]
not_affected_if: ["not-running-vigorconnect"]
published_at: "2021-10-13T16:15:07+00:00"
first_seen_at: "2026-10-23T19:11:51+00:00"
updated_at: "2026-10-23T22:29:05+00:00"
sources: [{"source": "kev", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2021-20123", "first_seen_at": "2026-10-23T19:11:51+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-20123", "first_seen_at": "2026-10-23T22:29:05+00:00"}]
---

# A local file inclusion vulnerability exists in Draytek VigorConnect 1.6.0-B3 in the file download functionality of…

DrayTek VigorConnect, a management server for DrayTek network devices, has a path traversal flaw in its DownloadFileServlet endpoint. An unauthenticated attacker can download arbitrary files from the server's operating system with root privileges.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:DrayTek VigorConnect affected ? fixed ?
- vendor:draytek vigorconnect affected = 1.6.0 fixed ?

## Fix

Apply the vendor mitigations per DrayTek instructions, or stop using VigorConnect if no mitigation is available (per CISA KEV required action).

## Timeline

- 2026-10-23T19:11:51+00:00 kev https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2021-20123
- 2026-10-23T22:29:05+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2021-20123

## From the sources

Draytek VigorConnect contains a path traversal vulnerability in the DownloadFileServlet endpoint. An unauthenticated attacker could leverage this vulnerability to download arbitrary files from the underlying operating system with root privileges.

CISA required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_