IRONSMITHINTEL
HIGHCVSS7.8
|
Actively Exploited
|CISA KEV|CVE-2025-62221|Auth: low — authenticated user|Reboot: required|Manual only

KB5071413: Windows Server Security Update (December 2025)

Microsoft Windows Cloud Files Mini Filter Driver contains a use after free vulnerability that can allow an authorized attacker to elevate privileges locally.

Published Dec 9, 2025 · Updated May 16, 2026
Why patchRisk explained in plain English
Worst-case scenarioIf unpatched

A local attacker, with a low-privilege account, can achieve full data confidentiality loss, arbitrary modification of data, complete denial of service or system unavailability. Federal agencies are required to remediate by 2025-12-30 under CISA BOD 22-01.

How the attack worksNo clicks needed

This is a Use After Free (CWE-416) vulnerability in Microsoft Windows. Use after free in Windows Cloud Files Mini Filter Driver allows an authorized attacker to elevate privileges locally. Exploitation requires local access, low attack complexity, a low-privilege authenticated account, and no user interaction required.

Am I affected?Quick check

Probably yes if any of these apply:

●Windows Administrators
●Systems Engineers
●IT Security
●Running windows 10 1809: v < 10.0.17763.8146; windows 10 21h2: v < 10.0.19044.6691; windows 10 22h2: v < 10.0.19045.6691; windows 11 23h2: v < 10.0.22631.6345; windows 11 24h2: v < 10.0.26100.7392; windows 11 25h2: v < 10.0.26200.7392; windows server 2019: v < 10.0.17763.8146; windows server 2022: v < 10.0.20348.4467; windows server 2022 23h2: v < 10.0.25398.2025; windows server 2025: v < 10.0.26100.7392
Fixed inKB5071413, KB5071417, KB5071542, KB5071544, KB5071546, KB5071547, KB5072014, KB5072033 (applies to 21 product versions) — build 10.0.17763.8146, 10.0.19044.6691+
Real-world incidentsWhat we've seen

CISA added this CVE to the Known Exploited Vulnerabilities catalog on 2025-12-09 based on evidence of active exploitation in the wild. Federal agencies required to remediate by 2025-12-30.

How to patch

Manual download

For air-gapped servers or out-of-band deployment. Microsoft Update Catalog returns every OS-version variant of this update.

↗ Microsoft Update CatalogKB5071413

Manual remediation steps

Apply the Microsoft Security Update

Microsoft has released an official security update that fixes this vulnerability.

Required KB Updates

    1
    KB5071413 — https://support.microsoft.com/help/5071413
    1
    KB5071417 — https://support.microsoft.com/help/5071417
    1
    KB5071542 — https://support.microsoft.com/help/5071542
    1
    KB5071544 — https://support.microsoft.com/help/5071544
    1
    KB5071546 — https://support.microsoft.com/help/5071546
    1
    KB5071547 — https://support.microsoft.com/help/5071547
    1
    KB5072014 — https://support.microsoft.com/help/5072014
    1
    KB5072033 — https://support.microsoft.com/help/5072033

Supersedes: KB5068779, KB5068781, KB5068787, KB5068791, KB5068840, KB5068861, KB5068865, KB5068966

Affected Products

    1
    Windows 10 Version 1809 for 32-bit Systems
    1
    Windows 10 Version 1809 for x64-based Systems
    1
    Windows 10 Version 21H2 for 32-bit Systems
    1
    Windows 10 Version 21H2 for ARM64-based Systems
    1
    Windows 10 Version 21H2 for x64-based Systems
    1
    Windows 10 Version 22H2 for 32-bit Systems
    1
    Windows 10 Version 22H2 for ARM64-based Systems
    1
    Windows 10 Version 22H2 for x64-based Systems
    1
    Windows 11 Version 23H2 for ARM64-based Systems
    1
    Windows 11 Version 23H2 for x64-based Systems
    1
    Windows 11 Version 24H2 for ARM64-based Systems
    1
    Windows 11 Version 24H2 for x64-based Systems
    1
    Windows 11 Version 25H2 for ARM64-based Systems
    1
    Windows 11 Version 25H2 for x64-based Systems
    1
    Windows Server 2019
    1
    Windows Server 2019 (Server Core installation)
    1
    Windows Server 2022
    1
    Windows Server 2022 (Server Core installation)
    1
    Windows Server 2022, 23H2 Edition (Server Core installation)
    1
    Windows Server 2025
    1
    (…1 more product versions)

Fixed Build Numbers

    1
    10.0.17763.8146
    1
    10.0.19044.6691
    1
    10.0.19045.6691
    1
    10.0.20348.4467
    1
    10.0.20348.4529
    1
    10.0.22631.6345
    1
    10.0.25398.2025
    1
    10.0.26100.7392
    1
    10.0.26100.7462
    1
    10.0.26200.7392
    1
    (…1 more builds)

Installation Methods

Windows Update (recommended)

1
Settings → Windows Update → Check for updates
2
The security update is offered if your system is in scope
3
Restart when prompted — a reboot IS required to complete the install

Microsoft Update Catalog (manual download)

1
Open https://catalog.update.microsoft.com
2
Search for KB5071413
3
Download the package matching your OS architecture and Windows build
4
Run the .msu installer with administrator privileges
5
Restart when prompted

WSUS / SCCM / Intune

Approve KB5071413 for the affected products in your update management console.

Microsoft Download Center Links

    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5071413
    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5071417
    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5071542
    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5071544
    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5071546
    1
    (…3 more)

Verification

Confirm the update is installed:

Get-HotFix | Where-Object { $_.HotFixID -in @('KB5071413','KB5071417','KB5071542','KB5071544','KB5071546','KB5071547','KB5072014','KB5072033') }

References

    1
    Microsoft Security Response Center: https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2025-62221
    1
    KB article: https://support.microsoft.com/help/5071413
    1
    KB article: https://support.microsoft.com/help/5071417
    1
    KB article: https://support.microsoft.com/help/5071542
    1
    NVD entry: https://nvd.nist.gov/vuln/detail/CVE-2025-62221
    1
    CISA KEV: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-62221

Discovery Credit

Microsoft Threat Intelligence Center (MSTIC) & Microsoft Security Response Center (MSRC)

PowerShell automationComing soon

No tested PowerShell script for this entry yet. We’re prioritising automation based on user demand.

References

↗ CVE-2025-62221↗ MSRC Advisory↗ NVD↗ KBKB5071413