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Wl Nu516u1 FirmwareOperating system · Wavlink

CVE-2026-3703

CRITICAL · 9.8 CVSS v3.1 Published 2026-03-08
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Public exploit Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Buffer overflow in Wavlink NU516U1 router's /cgi-bin/login.cgi (sub_401A10 function) allows remote attackers to write out-of-bounds memory via the ipaddr parameter, leading to potential remote code execution. The vulnerability is exploitable without authentication and a public exploit exists.

MitigationUpgrade to the vendor's fixed firmware version. If patching is immediately infeasible, disable remote administration interfaces and restrict access to the router's web interface to trusted networks.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Wl Nu516u1 FirmwareOperating system
Affected:= 251208

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify the router model
    Check the device label or web interface for the exact model number (NU516U1 or Wl Nu516u1)
    Affected if The device is a Wavlink NU516U1 router
  2. Check the installed firmware version
    Access the router's web admin panel and navigate to System or Administration settings to find the firmware version, or use the command 'cat /proc/version' or 'nvram get firm_version' via telnet/ssh if available
    Affected if The firmware version is exactly 251208
  3. Determine if remote web access is enabled
    Check the router's web interface for 'Remote Management', 'Remote Access', or 'Web Access from WAN' settings in the Administration or Security sections
    Affected if Remote administration/WAN access to the web interface is enabled and the router is directly exposed to the internet or untrusted networks
  4. Verify the login.cgi endpoint is reachable
    Attempt to access http://<router-ip>/cgi-bin/login.cgi from an external host (if remote access is enabled) to confirm the vulnerable endpoint is exposed
    Affected if The /cgi-bin/login.cgi endpoint responds and accepts the 'ipaddr' parameter without authentication

You are affected if you have a Wavlink NU516U1 router running firmware version 251208 with remote web management enabled, as the unauthenticated ipaddr parameter in /cgi-bin/login.cgi becomes remotely accessible.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade to the vendor's fixed firmware version. If patching is immediately infeasible, disable remote administration interfaces and restrict access to the router's web interface to trusted networks.

Recommended fix Moderate confidence

Latest available firmware version for Wavlink NU516U1 (contact vendor for specific version number)

  1. 1. Visit the official Wavlink support page at dl.wavlink.com and navigate to the NU516U1 product support section
  2. 2. Download the latest available firmware version for the NU516U1 device
  3. 3. Access the device administration web interface (typically at 192.168.1.1 or similar)
  4. 4. Navigate to the Firmware Upgrade or System Settings section
  5. 5. Upload the downloaded firmware file and initiate the upgrade process
  6. 6. Wait for the upgrade to complete and the device to reboot
  7. 7. Verify the new firmware version in the device admin interface
Caveat Firmware upgrades may reset device configuration to defaults; backup current settings before upgrading

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Wl Nu516u1 Firmware Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing6.0 h
  • Review / QA3.0 h
15.0 hours of engineering $2,560
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-3703 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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