# CVE-2024-40891: Zyxel DSL CPE OS Command Injection

> Authenticated attackers can execute OS commands on legacy Zyxel DSL CPE devices via Telnet management commands.

- **Severity:** High 8.8 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Yes, since 11 Feb 2025 (CISA KEV)
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 4 Feb 2025
- **Updated:** 21 Oct 2025
- **Also known as:** GHSA-pm4h-579g-cgqq

## What is CVE-2024-40891?

CVE-2024-40891 is a high-severity command injection vulnerability in Zyxel VMG4325-B10A firmware, published on 4 Feb 2025. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

**UNSUPPORTED WHEN ASSIGNED**
A post-authentication command injection vulnerability in the management commands of the legacy DSL CPE Zyxel VMG4325-B10A firmware version 1.00(AAFR.4)C0_20170615 could allow an authenticated attacker to execute operating system (OS) commands on an affected device via Telnet.

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

## Which versions are affected by CVE-2024-40891?

It affects 14 products.


Products: Zyxel Sbg3300-N000 Firmware, Zyxel Sbg3300-Nb00 Firmware, Zyxel Sbg3500-N000 Firmware, Zyxel Sbg3500-Nb00 Firmware, Zyxel Vmg1312-B10a Firmware, Zyxel Vmg1312-B10b Firmware, Zyxel Vmg1312-B10e Firmware, Zyxel Vmg3312-B10a Firmware, Zyxel Vmg3313-B10a Firmware, Zyxel Vmg3926-B10b Firmware, Zyxel Vmg4325-B10a Firmware, Zyxel Vmg4380-B10a Firmware, Zyxel Vmg8324-B10a Firmware, Zyxel Vmg8924-B10a Firmware.

## How do I fix CVE-2024-40891?

No fix has been published for CVE-2024-40891 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 4 Mar 2025.

## Is CVE-2024-40891 being exploited?

Yes. Attackers have exploited CVE-2024-40891 in the wild since at least 11 Feb 2025.

Public exploit code:

- From a bare PCB to root: hardware-hacking a ZyXEL P-870HN (BCM6368) over UART — CVE-2025-0890 + CVE-2024-40891, on my own hardware. (github_poc): https://github.com/Danyw24/zyxel-p870hn-hardware-hacking

## Other vulnerabilities in Zyxel VMG4325-B10A firmware

- [CVE-2024-40890](https://insights.sbomify.com/CVE-2024-40890/): Zyxel DSL CPE OS Command Injection (high 8.8, exploited in the wild)
- [CVE-2025-0890](https://insights.sbomify.com/CVE-2025-0890/): Hardcoded credentials in VMG4325-B10A firmware (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2024-40891 and fix it if it is affected.

What it is: CVE-2024-40891 is a high-severity command injection vulnerability in Zyxel VMG4325-B10A firmware, published on 4 Feb 2025. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: Yes. Attackers have exploited CVE-2024-40891 in the wild since at least 11 Feb 2025.

Affected product: Zyxel VMG4325-B10A 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-2024-40891/ (Markdown: https://insights.sbomify.com/CVE-2024-40891/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-40891
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-40891
- OSV: https://osv.dev/vulnerability/CVE-2024-40891

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-40891/
Summaries are generated and may contain mistakes; the official description above is the record.