# CVE-2026-4166: Wavlink WL-NU516U1 login.cgi sub_404F68 cross site scripting

> Remote attackers can inject malicious scripts via the login page, potentially leading to session hijacking or code execution on Wavlink WL-NU516U1 routers.

- **Severity:** Medium 5.1 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 15 Mar 2026
- **Updated:** 17 Mar 2026
- **Also known as:** GHSA-xhc2-6qjv-5jpp

## What is CVE-2026-4166?

CVE-2026-4166 is a medium-severity cross-site scripting vulnerability in Wavlink WL-NU516U1, published on 15 Mar 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

A vulnerability was found in Wavlink WL-NU516U1 240425. The impacted element is the function sub_404F68 of the file /cgi-bin/login.cgi. The manipulation of the argument homepage/hostname results in cross site scripting. The attack can be launched remotely. The exploit has been made public and could be used. The vendor was contacted early about this disclosure.

Weakness: CWE-94 (Improper Control of Generation of Code), CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-4166?


## How do I fix CVE-2026-4166?

No fix has been published for CVE-2026-4166 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-4166 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-4166 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-4166 and fix it if it is affected.

What it is: CVE-2026-4166 is a medium-severity cross-site scripting vulnerability in Wavlink WL-NU516U1, published on 15 Mar 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-4166 exists.

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-2026-4166/ (Markdown: https://insights.sbomify.com/CVE-2026-4166/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-4166
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-4166
- OSV: https://osv.dev/vulnerability/CVE-2026-4166

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-4166/
Summaries are generated and may contain mistakes; the official description above is the record.