# CVE-2026-71921: DrayTek VigorSwitch Multiple Models Pre-Authentication OS Command Injection via setget.cgi

> Remote attackers can execute arbitrary commands with root privileges on DrayTek VigorSwitch models via pre-authentication input in setget.cgi.

- **Severity:** Critical 9.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 24 Aug 2026
- **Updated:** 27 Aug 2026
- **Also known as:** GHSA-c34j-h938-5r57

## What is CVE-2026-71921?

CVE-2026-71921 is a critical command injection vulnerability in DrayTek Corporation VigorSwitch FX2120, published on 24 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Multiple DrayTek VigorSwitch models contain a pre-authentication command injection vulnerability in the setget.cgi interface. The vulnerability is caused by insufficient filtering of the pass field before command execution. A remote attacker can trigger this vulnerability via crafted input to execute arbitrary commands with root privileges.

Weakness: CWE-78 (Improper Neutralization of Special Elements used in an OS Command)

## Which versions are affected by CVE-2026-71921?


## How do I fix CVE-2026-71921?

No fix has been published for CVE-2026-71921 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-71921 being exploited?

There is no known exploitation of CVE-2026-71921 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-71921 and fix it if it is affected.

What it is: CVE-2026-71921 is a critical command injection vulnerability in DrayTek Corporation VigorSwitch FX2120, published on 24 Aug 2026. 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-2026-71921 in the wild and no public exploit code.

Affected product: DrayTek Corporation VigorSwitch FX2120. 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-2026-71921/ (Markdown: https://insights.sbomify.com/CVE-2026-71921/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-71921
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-71921
- OSV: https://osv.dev/vulnerability/CVE-2026-71921

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-71921/
Summaries are generated and may contain mistakes; the official description above is the record.