# CVE-2026-2566: Wavlink WL-NU516U1 adm.cgi sub_406194 stack-based overflow

> Remote attackers can trigger a stack-based buffer overflow in the Wavlink WL-NU516U1 router's adm.cgi script to execute arbitrary code.

- **Severity:** High 8.6 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/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:** 16 Feb 2026
- **Updated:** 23 Feb 2026
- **Also known as:** GHSA-jxpj-x8cw-h5ph

## What is CVE-2026-2566?

CVE-2026-2566 is a high-severity memory corruption vulnerability in Wavlink WL-NU516U1, published on 16 Feb 2026. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

A security vulnerability has been detected in Wavlink WL-NU516U1 up to 130/260. This affects the function sub_406194 of the file /cgi-bin/adm.cgi. Such manipulation of the argument firmware_url leads to stack-based buffer overflow. The attack can be launched remotely. The exploit has been disclosed publicly and may be used. The vendor was contacted early about this disclosure but did not respond in any way.

Weakness: CWE-121 (Stack-based Buffer Overflow), CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2026-2566?


## How do I fix CVE-2026-2566?

No fix has been published for CVE-2026-2566 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-2566 being exploited?

There is no known exploitation of CVE-2026-2566 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-2566 and fix it if it is affected.

What it is: CVE-2026-2566 is a high-severity memory corruption vulnerability in Wavlink WL-NU516U1, published on 16 Feb 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-2566 in the wild and no public exploit code.

Affected product: Wavlink WL-NU516U1. 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-2026-2566/ (Markdown: https://insights.sbomify.com/CVE-2026-2566/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-2566
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-2566
- OSV: https://osv.dev/vulnerability/CVE-2026-2566

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-2566/
Summaries are generated and may contain mistakes; the official description above is the record.