CVE-2026-4861 Wavlink WL-NU516U1 nas.cgi ftext stack-based overflow

High 8.7 Published 26 Mar 2026 Updated 26 Mar 2026

Remote attackers can trigger a stack-based buffer overflow in the Wavlink WL-NU516U1 NAS via the nas.cgi script, potentially executing arbitrary code.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2026-4861?

CVE-2026-4861 is a high-severity memory corruption vulnerability in Wavlink WL-NU516U1, published on 26 Mar 2026. Any signed-in user can exploit it over the network, with no action from the victim.

Official description

A weakness has been identified in Wavlink WL-NU516U1 260227. This vulnerability affects the function ftext of the file /cgi-bin/nas.cgi. This manipulation of the argument Content-Length causes stack-based buffer overflow. The attack can be initiated remotely. The exploit has been made available to the public and could be used for attacks. The vendor was contacted early about this disclosure but did not respond in any way.

Weakness: CWE-121, CWE-119

Which versions are affected by CVE-2026-4861?

It affects 1 product.

Products include Wavlink Wl-Nu516u1 Firmware.

How do I fix CVE-2026-4861?

No fix has been published for CVE-2026-4861 yet. Limit exposure of the affected software until one is available.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2026-4861 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-4861 exists.

Public exploit code: 1 proofs of concept on GitHub.

Sources

Also known as GHSA-f5jv-m3j9-f42p.