# CVE-2026-3613: Wavlink WL-NU516U1 login.cgi sub_401A0C stack-based overflow

> A remote attacker can trigger a stack-based buffer overflow in the login.cgi script of Wavlink WL-NU516U1 routers, potentially leading to arbitrary code execution.

- **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:** 6 Mar 2026
- **Updated:** 9 Mar 2026
- **Also known as:** GHSA-2fhq-mmhr-8hcv

## What is CVE-2026-3613?

CVE-2026-3613 is a high-severity memory corruption vulnerability in Wavlink WL-NU516U1, published on 6 Mar 2026. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

A vulnerability was identified in Wavlink WL-NU516U1 V240425. This vulnerability affects the function sub_401A0C of the file /cgi-bin/login.cgi. Such manipulation of the argument ipaddr leads to stack-based buffer overflow. It is possible to launch the attack remotely. The exploit is publicly available and might be used. The vendor was contacted early about this disclosure.

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-2026-3613?

It affects 1 product.


Products: Wavlink Wl-Nu516u1 Firmware.

## How do I fix CVE-2026-3613?

No fix has been published for CVE-2026-3613 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-3613 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-3613 exists.

## Other vulnerabilities in Wavlink WL-NU516U1

- [CVE-2026-3703](https://insights.sbomify.com/CVE-2026-3703/): Wavlink NU516U1 login.cgi sub_401A10 out-of-bounds write (critical 9.3)
- [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-2026-2615](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-2026-3613 and fix it if it is affected.

What it is: CVE-2026-3613 is a high-severity memory corruption vulnerability in Wavlink WL-NU516U1, published on 6 Mar 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-2026-3613 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-2026-3613/ (Markdown: https://insights.sbomify.com/CVE-2026-3613/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-3613
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-3613
- OSV: https://osv.dev/vulnerability/CVE-2026-3613

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-3613/
Summaries are generated and may contain mistakes; the official description above is the record.