# CVE-2026-3040: DrayTek Vigor 300B Web Management uploadlangs cgiGetFile os command injection

> Authenticated attackers can execute arbitrary OS commands via the web management interface of the end-of-life DrayTek Vigor 300B router.

- **Severity:** Medium 5.1 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 23 Feb 2026
- **Updated:** 25 Feb 2026
- **Also known as:** GHSA-9xx2-jmjv-w5vp

## What is CVE-2026-3040?

CVE-2026-3040 is a medium-severity command injection vulnerability in DrayTek Vigor 300B, published on 23 Feb 2026. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

A vulnerability was identified in DrayTek Vigor 300B up to 1.5.1.6. This affects the function cgiGetFile of the file /cgi-bin/mainfunction.cgi/uploadlangs of the component Web Management Interface. The manipulation of the argument File leads to os command injection. The attack may be initiated remotely. The exploit is publicly available and might be used. The vendor confirms that "300B is EoL, and this is an authenticated vulnerability. We don't plan to fix it." This vulnerability only affects products that are no longer supported by the maintainer.

Weakness: CWE-78 (Improper Neutralization of Special Elements used in an OS Command), CWE-77 (Improper Neutralization of Special Elements used in a Command)

## Which versions are affected by CVE-2026-3040?

It affects 1 product.


Products: Draytek Vigor300b Firmware.

## How do I fix CVE-2026-3040?

No fix has been published for CVE-2026-3040 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-3040 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-3040 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-3040 and fix it if it is affected.

What it is: CVE-2026-3040 is a medium-severity command injection vulnerability in DrayTek Vigor 300B, published on 23 Feb 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-3040 exists.

Affected product: DrayTek Vigor 300B. 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-2026-3040/ (Markdown: https://insights.sbomify.com/CVE-2026-3040/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-3040
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-3040
- OSV: https://osv.dev/vulnerability/CVE-2026-3040

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-3040/
Summaries are generated and may contain mistakes; the official description above is the record.