# CVE-2021-20712: Auth bypass in NEC Aterm devices

> A defect in the IPv6 firewall allows WAN-side attackers to access LAN-connected devices on NEC Aterm routers.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 26 Apr 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-c7vp-4m6m-jg9v

## What is CVE-2021-20712?

CVE-2021-20712 is a medium-severity authentication bypass vulnerability in NEC Aterm devices, published on 26 Apr 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Improper access control vulnerability in NEC Aterm WG2600HS firmware Ver1.5.1 and earlier, and Aterm WX3000HP firmware Ver1.1.2 and earlier allows a device connected to the LAN side to be accessed from the WAN side due to the defect in the IPv6 firewall function.

## Which versions are affected by CVE-2021-20712?

It affects 2 products.


Products: Nec Aterm Wg2600hs Firmware, Nec Aterm Wx3000hp Firmware.

## How do I fix CVE-2021-20712?

No fix has been published for CVE-2021-20712 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-20712 being exploited?

There is no known exploitation of CVE-2021-20712 in the wild and no public exploit code.

## Other vulnerabilities in NEC Aterm devices

- [CVE-2021-20711](https://insights.sbomify.com/CVE-2021-20711/): Command injection in Aterm WG2600HS (critical 9.8)
- [CVE-2020-5534](https://insights.sbomify.com/CVE-2020-5534/): Command injection in Aterm WG2600HS (high 8.0)
- [CVE-2020-5533](https://insights.sbomify.com/CVE-2020-5533/): Cross-site scripting in Aterm WG2600HS (medium 6.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-20712 and fix it if it is affected.

What it is: CVE-2021-20712 is a medium-severity authentication bypass vulnerability in NEC Aterm devices, published on 26 Apr 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-2021-20712 in the wild and no public exploit code.

Affected product: NEC Aterm devices. 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-2021-20712/ (Markdown: https://insights.sbomify.com/CVE-2021-20712/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-20712
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-20712
- OSV: https://osv.dev/vulnerability/CVE-2021-20712

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-20712/
Summaries are generated and may contain mistakes; the official description above is the record.