# CVE-2026-4621: Security feature bypass in Aterm GB1200PE

> Attackers can enable hidden telnet access on NEC Aterm routers, potentially leading to unauthorized remote control and code execution.

- **Severity:** Medium 6.3 (`CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/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:** 27 Mar 2026
- **Updated:** 10 Apr 2026
- **Also known as:** GHSA-v782-gww8-28q2

## What is CVE-2026-4621?

CVE-2026-4621 is a medium-severity vulnerability in NEC Platforms, Ltd. Aterm GB1200PE, published on 27 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Hidden Functionality vulnerability in NEC Platforms, Ltd. Aterm Series allows a attacker to enable telnet via network.

Weakness: CWE-912 (Hidden Functionality)

## Which versions are affected by CVE-2026-4621?

It affects 21 products.


Products: Nec Aterm W1200ex-Ms Firmware, Nec Aterm Wf1200cr Firmware, Nec Aterm Wg1200cr Firmware, Nec Aterm Wg1200hp2 Firmware, Nec Aterm Wg1200hp3 Firmware, Nec Aterm Wg1200hp4 Firmware, Nec Aterm Wg1200hs2 Firmware, Nec Aterm Wg1200hs3 Firmware, Nec Aterm Wg1200hs4 Firmware, Nec Aterm Wg1800hp3 Firmware, Nec Aterm Wg1800hp4 Firmware, Nec Aterm Wg1900hp2 Firmware, Nec Aterm Wg1900hp Firmware, Nec Aterm Wg2600hm4 Firmware, Nec Aterm Wg2600hp4 Firmware, Nec Aterm Wg2600hs2 Firmware, Nec Aterm Wg2600hs Firmware, Nec Aterm Wx1500hp Firmware, Nec Aterm Wx3000hp2 Firmware, Nec Aterm Wx3000hp Firmware and 1 more.

## How do I fix CVE-2026-4621?

No fix has been published for CVE-2026-4621 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-4621 being exploited?

There is no known exploitation of CVE-2026-4621 in the wild and no public exploit code.

## Other vulnerabilities in NEC Platforms, Ltd. Aterm GB1200PE

- [CVE-2026-4309](https://insights.sbomify.com/CVE-2026-4309/): Missing authorization in Aterm GB1200PE (medium 6.3)
- [CVE-2021-20680](https://insights.sbomify.com/CVE-2021-20680/): Cross-site scripting in NEC Aterm devices (medium 6.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-4621 and fix it if it is affected.

What it is: CVE-2026-4621 is a medium-severity vulnerability in NEC Platforms, Ltd. Aterm GB1200PE, published on 27 Mar 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-2026-4621 in the wild and no public exploit code.

Affected product: NEC Platforms, Ltd. Aterm GB1200PE. 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-2026-4621/ (Markdown: https://insights.sbomify.com/CVE-2026-4621/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-4621
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-4621
- OSV: https://osv.dev/vulnerability/CVE-2026-4621

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-4621/
Summaries are generated and may contain mistakes; the official description above is the record.