# CVE-2021-20680: Cross-site scripting in NEC Aterm devices

> Remote attackers can inject arbitrary scripts into NEC Aterm routers, potentially compromising user sessions and device security.

- **Severity:** Medium 6.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 26 Apr 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-qrw9-9x9v-8v9p

## What is CVE-2021-20680?

CVE-2021-20680 is a medium-severity cross-site scripting vulnerability in NEC Aterm devices, published on 26 Apr 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

Cross-site scripting vulnerability in NEC Aterm devices (Aterm WG1900HP2 firmware Ver.1.3.1 and earlier, Aterm WG1900HP firmware Ver.2.5.1 and earlier, Aterm WG1800HP4 firmware Ver.1.3.1 and earlier, Aterm WG1800HP3 firmware Ver.1.5.1 and earlier, Aterm WG1200HS2 firmware Ver.2.5.0 and earlier, Aterm WG1200HP3 firmware Ver.1.3.1 and earlier, Aterm WG1200HP2 firmware Ver.2.5.0 and earlier, Aterm W1200EX firmware Ver.1.3.1 and earlier, Aterm W1200EX-MS firmware Ver.1.3.1 and earlier, Aterm WG1200HS firmware all versions Aterm WG1200HP firmware all versions Aterm WF800HP firmware all versions Aterm WF300HP2 firmware all versions Aterm WR8165N firmware all versions Aterm W500P firmware all versions, and Aterm W300P firmware all versions) allows remote attackers to inject arbitrary script or HTML via unspecified vectors.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2021-20680?

It affects 17 products.


Products: Nec Aterm W1200ex-Ms Firmware, Nec Aterm W1200ex Firmware, Nec Aterm W300p Firmware, Nec Aterm W500p Firmware, Nec Aterm Wf300hp2 Firmware, Nec Aterm Wf800hp Firmware, Nec Aterm Wg1200hp2 Firmware, Nec Aterm Wg1200hp3 Firmware, Nec Aterm Wg1200hp Firmware, Nec Aterm Wg1200hs2 Firmware, Nec Aterm Wg1200hs3 Firmware, Nec Aterm Wg1200hs Firmware, Nec Aterm Wg1800hp3 Firmware, Nec Aterm Wg1800hp4 Firmware, Nec Aterm Wg1900hp2 Firmware, Nec Aterm Wg1900hp Firmware, Nec Aterm Wr8165n Firmware.

## How do I fix CVE-2021-20680?

No fix has been published for CVE-2021-20680 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-20680 being exploited?

There is no known exploitation of CVE-2021-20680 in the wild and no public exploit code.

## Other vulnerabilities in NEC Aterm devices

- [CVE-2026-4309](https://insights.sbomify.com/CVE-2026-4309/): Missing authorization in Aterm GB1200PE (medium 6.3)
- [CVE-2026-4621](https://insights.sbomify.com/CVE-2026-4621/): Security feature bypass in Aterm GB1200PE (medium 6.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-20680 and fix it if it is affected.

What it is: CVE-2021-20680 is a medium-severity cross-site scripting vulnerability in NEC Aterm devices, published on 26 Apr 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2021-20680 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-2021-20680/ (Markdown: https://insights.sbomify.com/CVE-2021-20680/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-20680
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-20680
- OSV: https://osv.dev/vulnerability/CVE-2021-20680

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-20680/
Summaries are generated and may contain mistakes; the official description above is the record.