# CVE-2026-3703: Wavlink NU516U1 login.cgi sub_401A10 out-of-bounds write

> Remote attackers can trigger an out-of-bounds write in the login CGI script, potentially leading to code execution on Wavlink NU516U1 routers.

- **Severity:** Critical 9.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 8 Mar 2026
- **Updated:** 10 Mar 2026
- **Also known as:** GHSA-6rfc-r3c7-7f5j

## What is CVE-2026-3703?

CVE-2026-3703 is a critical memory corruption vulnerability in Wavlink NU516U1, published on 8 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A flaw has been found in Wavlink NU516U1 251208. This affects the function sub_401A10 of the file /cgi-bin/login.cgi. Executing a manipulation of the argument ipaddr can lead to out-of-bounds write. The attack may be performed from remote. The exploit has been published and may be used. Upgrading the affected component is recommended. The vendor was contacted early, responded in a very professional manner and quickly released a fixed version of the affected product.

Weakness: CWE-787 (Out-of-bounds Write), CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2026-3703?

It affects 1 product.


Products: Wavlink Wl-Nu516u1 Firmware.

## How do I fix CVE-2026-3703?

No fix has been published for CVE-2026-3703 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-3703 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-3703 exists.

## Other vulnerabilities in Wavlink NU516U1

- [CVE-2026-4861](https://insights.sbomify.com/CVE-2026-4861/): Wavlink WL-NU516U1 nas.cgi ftext stack-based overflow (high 8.7)
- [CVE-2026-3612](https://insights.sbomify.com/CVE-2026-3612/): Wavlink WL-NU516U1 OTA Online Upgrade adm.cgi sub_405AF4 command injection (high 8.6)
- [CVE-2026-3613](https://insights.sbomify.com/CVE-2026-3613/): Wavlink WL-NU516U1 login.cgi sub_401A0C stack-based overflow (high 8.6)
- [CVE-2026-2615](https://insights.sbomify.com/CVE-2026-2615/): Wavlink WL-NU516U1 firewall.cgi singlePortForwardDelete command injection (high 8.6)
- [CVE-2026-2567](https://insights.sbomify.com/CVE-2026-2567/): Wavlink WL-NU516U1 nas.cgi sub_401218 stack-based overflow (high 8.6)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-3703 and fix it if it is affected.

What it is: CVE-2026-3703 is a critical memory corruption vulnerability in Wavlink NU516U1, published on 8 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-3703 exists.

Affected product: Wavlink 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-2026-3703/ (Markdown: https://insights.sbomify.com/CVE-2026-3703/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-3703
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-3703
- OSV: https://osv.dev/vulnerability/CVE-2026-3703

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-3703/
Summaries are generated and may contain mistakes; the official description above is the record.