# CVE-2021-4030: Cross-site request forgery in ARMOR Z1 (NBG6816) firmware

> An attacker can execute arbitrary commands on Zyxel ARMOR devices by tricking a local user into visiting a malicious website via CSRF.

- **Severity:** High 8.0 (`CVSS:3.1/AV:A/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 22 Feb 2022
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-f5hq-fhh6-8vh6

## What is CVE-2021-4030?

CVE-2021-4030 is a high-severity vulnerability in Zyxel ARMOR Z1 (NBG6816) firmware, published on 22 Feb 2022. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

A cross-site request forgery vulnerability in the HTTP daemon of the Zyxel ARMOR Z1/Z2 firmware could allow an attacker to execute arbitrary commands if they coerce or trick a local user to visit a compromised website with malicious scripts.

Weakness: CWE-352 (Cross-Site Request Forgery)

## Which versions are affected by CVE-2021-4030?

It affects 2 products.


Products: Zyxel Nbg6816 Firmware, Zyxel Nbg6817 Firmware.

## How do I fix CVE-2021-4030?

No fix has been published for CVE-2021-4030 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-4030 being exploited?

There is no known exploitation of CVE-2021-4030 in the wild and no public exploit code.

## Other vulnerabilities in Zyxel ARMOR Z1 (NBG6816) firmware

- [CVE-2021-4029](https://insights.sbomify.com/CVE-2021-4029/): Command injection in ARMOR Z1 (NBG6816) firmware (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-4030 and fix it if it is affected.

What it is: CVE-2021-4030 is a high-severity vulnerability in Zyxel ARMOR Z1 (NBG6816) firmware, published on 22 Feb 2022. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2021-4030 in the wild and no public exploit code.

Affected product: Zyxel ARMOR Z1 (NBG6816) firmware. 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-2021-4030/ (Markdown: https://insights.sbomify.com/CVE-2021-4030/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-4030
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-4030
- OSV: https://osv.dev/vulnerability/CVE-2021-4030

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-4030/
Summaries are generated and may contain mistakes; the official description above is the record.