# CVE-2021-20125: File upload in Draytek VigorConnect

> Unauthenticated attackers can upload arbitrary files to any location with root privileges, leading to remote code execution on Draytek VigorConnect devices.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 13 Oct 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-j2q4-4x34-58rx

## What is CVE-2021-20125?

CVE-2021-20125 is a critical vulnerability in Draytek VigorConnect, published on 13 Oct 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An arbitrary file upload and directory traversal vulnerability exists in the file upload functionality of DownloadFileServlet in Draytek VigorConnect 1.6.0-B3. An unauthenticated attacker could leverage this vulnerability to upload files to any location on the target operating system with root privileges.

Weakness: CWE-434 (Unrestricted Upload of File with Dangerous Type), CWE-22 (Improper Limitation of a Pathname to a Restricted Directory)

## Which versions are affected by CVE-2021-20125?

It affects 1 product.


Products: Draytek Vigorconnect.

## How do I fix CVE-2021-20125?

No fix has been published for CVE-2021-20125 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-20125 being exploited?

There is no known exploitation of CVE-2021-20125 in the wild and no public exploit code.

## Other vulnerabilities in Draytek VigorConnect

- [CVE-2021-20123](https://insights.sbomify.com/CVE-2021-20123/): Draytek VigorConnect Path Traversal Vulnerability (high 7.5, exploited in the wild)
- [CVE-2021-20124](https://insights.sbomify.com/CVE-2021-20124/): Draytek VigorConnect Path Traversal Vulnerability (high 7.5, exploited in the wild)
- [CVE-2021-20126](https://insights.sbomify.com/CVE-2021-20126/): Cross-site request forgery in Draytek VigorConnect (high 8.8)
- [CVE-2021-20127](https://insights.sbomify.com/CVE-2021-20127/): Path traversal in Draytek VigorConnect (high 8.1)
- [CVE-2021-20129](https://insights.sbomify.com/CVE-2021-20129/): Information disclosure in Draytek VigorConnect (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-20125 and fix it if it is affected.

What it is: CVE-2021-20125 is a critical vulnerability in Draytek VigorConnect, published on 13 Oct 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-20125 in the wild and no public exploit code.

Affected product: Draytek VigorConnect. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2021-20125/ (Markdown: https://insights.sbomify.com/CVE-2021-20125/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-20125
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-20125
- OSV: https://osv.dev/vulnerability/CVE-2021-20125

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-20125/
Summaries are generated and may contain mistakes; the official description above is the record.