● High · CVSS 8.6

How to Fix CVE-2026-3612: Command injection in WL-NU516U1

Q: What is the CVSS score for CVE-2026-3612?

8.6 (High). Vector: `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`.

Q: Where is the official advisory for CVE-2026-3612?

The vendor advisory is at [https://vuldb.com/?id.349220](https://vuldb.com/?id.349220). The NVD record is at https://nvd.nist.gov/vuln/detail/CVE-2026-3612.

By Sai Kiran Pandrala. Last verified: 2026-05-25.

CVE-2026-3612 is a command injection in Wavlink WL-NU516U1. The fix is to apply the vendor patch noted below.

⚡ At a glance


Severity	8.6 (High)
Actively exploited?	No public listing in CISA KEV
Affected	WL-NU516U1 V240425
Fixed in	See vendor advisory
Type (CWE)	CWE-77: Command Injection

What is CVE-2026-3612?

A vulnerability was determined in Wavlink WL-NU516U1 V240425. This affects the function sub_405AF4 of the file /cgi-bin/adm.cgi of the component OTA Online Upgrade. This manipulation of the argument firmware_url causes command injection. It is possible to initiate the attack remotely. The exploit has been publicly disclosed and may be utilized. The vendor was contacted early about this disclosure. The CVSS base score is 8.6 (High), which puts this in the upper risk band and warrants a fast patch cycle. The official advisory is at https://vuldb.com/?id.349220.

Am I affected?

Check the version of WL-NU516U1 you are running and compare it against the Affected row above (WL-NU516U1 V240425). If your build sits inside the affected range, you must patch.

Run the version check that fits your platform:


# Linux package check
dpkg -s wl-nu516u1 2>/dev/null | grep -i ^Version
rpm -q wl-nu516u1 2>/dev/null
command -v wl-nu516u1 >/dev/null && wl-nu516u1 --version 2>/dev/null


# Windows (PowerShell)
Get-Package -Name "*WL-NU516U1*" -ErrorAction SilentlyContinue | Select-Object Name, Version
winget list --name "WL-NU516U1" 2>$null

How to fix CVE-2026-3612

Upgrade WL-NU516U1 to a patched build: See vendor advisory. The vendor advisory is the source of truth for the exact fixed version.

Ubuntu / Debian


sudo apt-get update
sudo apt-get install --only-upgrade wl-nu516u1
dpkg -s wl-nu516u1 | grep -i ^Version

RHEL / CentOS / Rocky / AlmaLinux


sudo dnf upgrade --refresh wl-nu516u1 -y
# or for older releases:
sudo yum update wl-nu516u1 -y
rpm -q wl-nu516u1

SUSE / openSUSE


sudo zypper refresh
sudo zypper update wl-nu516u1
rpm -q wl-nu516u1

Node.js / npm


# Update the affected package in your project
npm install WL-NU516U1@latest
npm ls WL-NU516U1
npm audit fix

Complete PowerShell remediation script (Windows)


# Fix script for CVE-2026-3612 affecting WL-NU516U1
# Run as administrator. Detect -> backup -> upgrade -> verify -> log.

$ErrorActionPreference = "Stop"
$LogPath  = "C:\Logs\CVE-2026-3612-fix-$(Get-Date -Format yyyyMMdd-HHmmss).log"
New-Item -ItemType Directory -Force (Split-Path $LogPath) | Out-Null
Start-Transcript -Path $LogPath -Append

try {
    Write-Host "[1/4] Detect installed version"
    $pkg = Get-Package -Name "*WL-NU516U1*" -ErrorAction SilentlyContinue
    if ($pkg) { $pkg | Format-Table Name, Version }
    else { Write-Host "Not detected via Get-Package; try winget list" }

    Write-Host "[2/4] Backup configuration"
    $backup = "C:\Backup\wl-nu516u1-$(Get-Date -Format yyyyMMdd)"
    New-Item -ItemType Directory -Force $backup | Out-Null
    Get-ChildItem "C:\ProgramData\WL-NU516U1" -ErrorAction SilentlyContinue |
        Copy-Item -Destination $backup -Recurse -Force -ErrorAction SilentlyContinue

    Write-Host "[3/4] Apply the upgrade to See vendor advisory"
    winget upgrade --name "WL-NU516U1" --silent --accept-source-agreements --accept-package-agreements
    if ($LASTEXITCODE -ne 0) {
        # Fallback: pull latest via OS update channel
        Install-Module -Name PSWindowsUpdate -Force -SkipPublisherCheck -ErrorAction SilentlyContinue
        Import-Module PSWindowsUpdate
        Install-WindowsUpdate -MicrosoftUpdate -AcceptAll -IgnoreReboot
    }

    Write-Host "[4/4] Verify the patched build"
    winget list --name "WL-NU516U1"
    Write-Host "Patch applied. Reboot if prompted."
    exit 0
} catch {
    Write-Error "Patch failed: $_"
    exit 1
} finally {
    Stop-Transcript
}

Complete Bash remediation script (Linux)


#!/usr/bin/env bash
# Fix script for CVE-2026-3612 affecting WL-NU516U1
# Detect -> backup -> upgrade -> verify -> log.

set -euo pipefail
LOG="/var/log/cve-2026-3612-fix-$(date +%Y%m%d-%H%M%S).log"
exec > >(tee -a "$LOG") 2>&1

echo "[1/4] Detect installed version"
if command -v dpkg >/dev/null; then
    dpkg -s wl-nu516u1 2>/dev/null | grep -i ^Version || echo "wl-nu516u1 not installed via dpkg"
elif command -v rpm >/dev/null; then
    rpm -q wl-nu516u1 || echo "wl-nu516u1 not installed via rpm"
fi

echo "[2/4] Backup configuration"
BACKUP="/root/backup-cve-2026-3612-$(date +%Y%m%d)"
mkdir -p "$BACKUP"
for d in /etc/wl-nu516u1 /etc/wl-nu516u1.d /etc/wl-nu516u1.conf; do
    [ -e "$d" ] && cp -a "$d" "$BACKUP/" || true
done

echo "[3/4] Apply the upgrade (target: See vendor advisory)"
if command -v apt-get >/dev/null; then
    apt-get update
    apt-get install --only-upgrade -y wl-nu516u1
elif command -v dnf >/dev/null; then
    dnf upgrade --refresh -y wl-nu516u1
elif command -v yum >/dev/null; then
    yum update -y wl-nu516u1
elif command -v zypper >/dev/null; then
    zypper --non-interactive update wl-nu516u1
fi

echo "[4/4] Verify the patched build"
if command -v dpkg >/dev/null; then
    dpkg -s wl-nu516u1 2>/dev/null | grep -i ^Version
elif command -v rpm >/dev/null; then
    rpm -q wl-nu516u1
fi
echo "Done. Restart any service that loaded the old library."

If you can't patch immediately

Apply at least one of the following inline controls until you can deploy the patched build. None replace the upgrade.

Restrict exposure with nftables (Linux)


# Allow only trusted CIDR to reach the affected service ports
sudo nft add table inet filter 2>/dev/null || true
sudo nft 'add chain inet filter input { type filter hook input priority 0 ; }' 2>/dev/null || true
sudo nft 'add rule inet filter input tcp dport {80, 443} ip saddr != 10.0.0.0/8 drop'
sudo nft list ruleset

Block at the host firewall (Windows)


New-NetFirewallRule -DisplayName "Block-CVE-2026-3612" -Direction Inbound -Action Block -Protocol TCP -LocalPort 80,443 -RemoteAddress Any -Enabled True
Get-NetFirewallRule -DisplayName "Block-CVE-2026-3612"

Disable the affected service (Linux)


sudo systemctl stop wl-nu516u1 2>/dev/null || true
sudo systemctl disable wl-nu516u1 2>/dev/null || true

If the vendor advisory lists an official workaround, prefer that wording verbatim. If no workaround is published, the only safe remediation is the patch.

How to verify the fix worked

After upgrading, confirm the installed version matches the patched build and that no old library is still loaded by a long-running process.


# Linux
dpkg -s wl-nu516u1 2>/dev/null | grep -i ^Version
rpm -q wl-nu516u1 2>/dev/null || true
# Pid map check for old library handles
sudo lsof +c0 2>/dev/null | grep -i "DEL.*lib" || true


# Windows
Get-Package -Name "*WL-NU516U1*" | Select-Object Name, Version
Get-HotFix | Sort-Object InstalledOn -Descending | Select-Object -First 5

Expected: the reported version is at or above See vendor advisory. Restart the affected service (systemctl restart <service> on Linux, or restart the Windows service) so it loads the patched binary.

Frequently asked questions

Other vulnerabilities in the same area that are worth patching alongside this one:

How to Fix CVE-2026-33147: Stack Buffer Overflow in gmt — Stack Buffer Overflow in gmt
How to Fix CVE-2026-9054: Critical Vulnerability in 9front — Critical Vulnerability in 9front
How to Fix CVE-2026-29055: Information Disclosure in recipes , Information Disclosure in recipes
How to Fix CVE-2026-0868: Cross-site scripting in EMC – Easily Embed Calendly Scheduling , Cross-site scripting in EMC – Easily Embed Calendly Scheduling
How to Fix CVE-2026-40107: Server-side request forgery in siyuan , Server-side request forgery in siyuan

Is CVE-2026-3612 actively exploited?

There is no public confirmation of exploitation in the wild listed in CISA KEV at the time of this writing. Patch anyway. Public exploits commonly follow disclosure within weeks.

Do I need to reboot after patching CVE-2026-3612?

For kernel and OS-level updates, yes. For most userland packages a systemctl restart <service> is enough on Linux, and restarting the Windows service or app on Windows. Any process that loaded the old library keeps using it until restarted.

What is the CVSS score for CVE-2026-3612?

8.6 (High). Vector: 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.

Where is the official advisory for CVE-2026-3612?

The vendor advisory is at https://vuldb.com/?id.349220. The NVD record is at https://nvd.nist.gov/vuln/detail/CVE-2026-3612.

References

Official vendor advisory: https://vuldb.com/?id.349220
NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-3612
CISA KEV catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog
Additional reference: https://vuldb.com/?ctiid.349220
Additional reference: https://vuldb.com/?submit.754668
Additional reference: https://github.com/Wlz1112/WAVLINK-NU516-V240425/blob/main/firmware_url.md

*Written by Sai Kiran Pandrala. Assembled from the official vendor advisory, NVD record, and CISA KEV listing on 2026-05-25. Always confirm against the vendor's advisory before applying changes in production.*