● High · CVSS 7

How to Fix CVE-2026-25179: CWE-1287: Improper Validation of Specified Type of Input

Q: Is CVE-2026-25179 being actively exploited?

Not at the time of writing. It is not listed in CISA's Known Exploited Vulnerabilities catalog. That status can change, so monitor the vendor advisory and the KEV catalog if the system is exposed.

Q: How severe is CVE-2026-25179?

CVSS rates it 7 (High). Use that score to set your patch priority next to the other items in your queue.

Q: Do I have to take Windows 10 Version 1607 offline to apply the patch?

It depends on the deployment. High-availability or clustered installs can usually patch one node at a time with no full outage. Standalone installs typically need a short restart. Always follow the vendor's documented upgrade steps.

Q: What if my vulnerability scanner still flags CVE-2026-25179 after I patch?

Re-run the scan after a service restart, then confirm the scanner's plugin set is up to date. Some scanners detect by banner version only and lag the official fix metadata by a release.

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

How to Fix CVE-2026-25185: Windows Shell Link Processing Spoofing in Windows 10 Version 1607 — Windows Shell Link Processing Spoofing in Windows 10 Version 1607
How to Fix CVE-2026-21235: Use-After-Free in Windows 10 Version 1607 — Use-After-Free in Windows 10 Version 1607
How to Fix CVE-2026-33096: Out-of-bounds read in Microsoft Windows , Out-of-bounds read in Microsoft Windows
How to Fix CVE-2026-0390: Cwe-807: reliance on untrusted inputs in in Microsoft Windows , Cwe-807: reliance on untrusted inputs in in Microsoft Windows
How to Fix CVE-2026-40402: Use-After-Free in Windows 11 version 22H3 , Use-After-Free in Windows 11 version 22H3

*By Sai Kiran Pandrala*

⚡ At a glance


Severity	CVSS 7, High
Actively exploited?	No
Affected	Microsoft Windows 10 Version 1607 (10.0.14393.0 < 10.0.14393.8957); Microsoft Windows 10 Version 1809 (10.0.17763.0 < 10.0.17763.8511); Microsoft Windows 10 Version 21H2 (10.0.19044.0 < 10.0.19044.7058); Microsoft Windows 10 Version 22H2 (10.0.19045.0 < 10.0.19045.7058)
Fixed in	10.0.14393.8957, 10.0.17763.8511, 10.0.19044.7058, 10.0.19045.7058
Type (CWE)	CWE-1287: Improper Validation of Specified Type of Input

What is CVE-2026-25179?

Improper validation of specified type of input in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.

In practical terms, a successful attacker gets compromise of the affected component as described in the vendor advisory. There is no confirmed in-the-wild exploitation listed in CISA's KEV catalog at the time of writing, but the CVSS rating still warrants prompt patching.

Am I affected?

You're affected if you run Microsoft Windows 10 Version 1607 at any version in the Affected row above. Use these probes to find your installed build:


[System.Environment]::OSVersion.Version
Get-HotFix | Sort-Object InstalledOn -Descending | Select-Object -First 10

How to fix CVE-2026-25179

The primary fix is to upgrade to the patched build listed in the Fixed in row above (10.0.14393.8957, 10.0.17763.8511, 10.0.19044.7058, 10.0.19045.7058). Pick the platform that matches your install and run the commands below.

Windows / Windows Server (PowerShell, admin)


# Apply the most recent cumulative update
Install-Module -Name PSWindowsUpdate -Force -Scope CurrentUser
Import-Module PSWindowsUpdate
Get-WindowsUpdate -MicrosoftUpdate -AcceptAll -Install -AutoReboot

Or install a specific KB manually


$kb = 'KB-from-advisory'   # replace with the KB ID listed in the MSRC advisory
$msu = "$env:TEMP\$kb.msu"
Invoke-WebRequest -Uri "https://catalog.update.microsoft.com/Search.aspx?q=$kb" -UseBasicParsing
# Download the matching .msu from the catalog, then:
Start-Process -FilePath 'wusa.exe' -ArgumentList "$msu /quiet /norestart" -Wait
Restart-Computer -Force

PowerShell script (Windows) - detect, back up, upgrade, verify, log


# Run as Administrator
$ErrorActionPreference = 'Stop'
$log = "$env:ProgramData\Windows10Version1607-Patch-CVE-2026-25179.log"
function Write-Log($msg) { "$(Get-Date -Format s)  $msg" | Tee-Object -FilePath $log -Append }

Write-Log "Starting CVE-2026-25179 remediation for Microsoft Windows 10 Version 1607"

# 1. Detect: replace the path/version probe with one valid for your install
$installed = (Get-WmiObject -Class Win32_Product |
    Where-Object { $_.Name -like '*Windows*' } |
    Select-Object -First 1 -ExpandProperty Version)
Write-Log "Detected version: $installed"

if (-not $installed) {
    Write-Log "Product not installed on this host; nothing to do."
    return
}
if ([version]$installed -ge [version]'10.0.14393.8957') {
    Write-Log "Already at fixed version $installed; no action needed."
    return
}

# 2. Backup configuration to a timestamped folder
$backup = "$env:ProgramData\Windows10Version1607-Backup-$(Get-Date -Format yyyyMMdd-HHmm)"
New-Item -ItemType Directory -Path $backup -Force | Out-Null
# Adjust the source path to match your install
$src = "$env:ProgramFiles\Microsoft\Windows 10 Version 1607"
if (Test-Path $src) { Copy-Item -Path $src -Destination $backup -Recurse -Force }
Write-Log "Backed up config to $backup"

# 3. Apply the patched installer (place the verified file on a share or staging path)
$installer = "$env:TEMP\Windows10Version1607-10.0.14393.8957.msi"
if (-not (Test-Path $installer)) {
    throw "Patched installer not found at $installer. Stage it from your software repo first."
}
Start-Process msiexec.exe -ArgumentList "/i `"$installer`" /qn /norestart" -Wait
Write-Log "Installer finished"

# 4. Verify
$verify = (Get-WmiObject -Class Win32_Product |
    Where-Object { $_.Name -like '*Windows*' } |
    Select-Object -First 1 -ExpandProperty Version)
if ([version]$verify -ge [version]'10.0.14393.8957') {
    Write-Log "SUCCESS: now at $verify (>= 10.0.14393.8957)"
} else {
    Write-Log "FAILURE: still at $verify after install"
    exit 1
}

Bash script (Linux) - detect, back up, upgrade, verify, log


#!/usr/bin/env bash
set -euo pipefail
LOG=/var/log/windows-10-version-1607-patch-cve-2026-25179.log
log()  { echo "$(date -Iseconds)  $*" | tee -a "$LOG"; }

log "Starting CVE-2026-25179 remediation for Microsoft Windows 10 Version 1607"

# 1. Detect installed version (works for deb and rpm packages)
if command -v dpkg >/dev/null && dpkg -s windows-10-version-1607 >/dev/null 2>&1; then
    CURRENT=$(dpkg-query -W -f='${Version}' windows-10-version-1607)
    PKG_MGR=apt
elif command -v rpm >/dev/null && rpm -q windows-10-version-1607 >/dev/null 2>&1; then
    CURRENT=$(rpm -q --queryformat '%{VERSION}' windows-10-version-1607)
    PKG_MGR=dnf
else
    log "windows-10-version-1607 not installed via apt or rpm; check your package manager or vendor instructions."
    exit 0
fi
log "Detected: windows-10-version-1607=$CURRENT (manager=$PKG_MGR)"

# 2. Backup config
BACKUP=/var/backups/windows-10-version-1607-$(date +%Y%m%d-%H%M)
mkdir -p "$BACKUP"
for d in /etc/windows-10-version-1607 /etc/${pkg%%-*} ; do
    [ -d "$d" ] && cp -a "$d" "$BACKUP/" && log "Backed up $d to $BACKUP"
done

# 3. Upgrade
if [ "$PKG_MGR" = apt ]; then
    sudo apt-get update -y
    sudo apt-get install --only-upgrade -y windows-10-version-1607
else
    sudo dnf upgrade --security -y windows-10-version-1607
fi

# 4. Verify
if [ "$PKG_MGR" = apt ]; then
    NEW=$(dpkg-query -W -f='${Version}' windows-10-version-1607)
else
    NEW=$(rpm -q --queryformat '%{VERSION}' windows-10-version-1607)
fi
log "After upgrade: $NEW"

# Optionally compare against 10.0.14393.8957 with dpkg --compare-versions or sort -V
log "Done. Restart the affected service if the package install did not."

If you can't patch immediately

These are runnable hardening commands. They reduce blast radius but they're not a replacement for the vendor patch.

No official vendor workaround is published for this CVE; patching is the only documented fix. The runnable hardening below is generic defense in depth, not a substitute for the patch.

Restrict the affected service to trusted networks (Linux):


# Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-25179
# Replace <port> with the affected service port and 10.0.0.0/24 with your admin subnet
sudo iptables -A INPUT -p tcp --dport <port> -s 10.0.0.0/24 -j ACCEPT
sudo iptables -A INPUT -p tcp --dport <port> -j DROP

Windows Firewall equivalent:


# Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-25179
New-NetFirewallRule -DisplayName 'Allow affected service from admin subnet' \
    -Direction Inbound -Action Allow -Protocol TCP -LocalPort <port> -RemoteAddress 10.0.0.0/24
New-NetFirewallRule -DisplayName 'Block affected service from everywhere else' \
    -Direction Inbound -Action Block -Protocol TCP -LocalPort <port>

How to verify the fix worked

Run the version probe again and confirm the running build matches the Fixed in row above.


Get-HotFix | Sort-Object InstalledOn -Descending | Select-Object -First 5

Expected output: the KB ID listed in the vendor advisory appears with an InstalledOn date that matches your patch window.

Then re-run any vulnerability scanner you used previously and confirm the finding for CVE-2026-25179 has cleared. Sweep your logs for the indicators of compromise listed in the vendor or CISA advisory, especially if the system was internet-reachable during the disclosure window.

Frequently asked questions

Is CVE-2026-25179 being actively exploited?