IRONSMITHINTEL
HIGHCVSS7.0
|
Actively Exploited
|CISA KEV|CVE-2022-21882|Auth: low — authenticated user|Reboot: required|Manual only

KB5009543: Windows Server Security Update (January 2022)

Microsoft Win32k contains an unspecified vulnerability that allows for privilege escalation.

Published Jan 11, 2022 · 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 2022-02-18 under CISA BOD 22-01.

How the attack worksNo clicks needed

This is a Out-of-bounds Write (CWE-787) vulnerability in Microsoft Win32k. Exploitation requires local access, higher attack complexity, a low-privilege authenticated account, and no user interaction required.

Am I affected?Quick check

Probably yes if any of these apply:

●IT Security
●Running windows 10 1809: v < 10.0.17763.2452; windows 10 1909: v < 10.0.18363.2037; windows 10 20h2: v < 10.0.19042.1466; windows 10 21h1: v < 10.0.19043.1466; windows 10 21h2: v < 10.0.19044.1466; windows 11 21h2: v < 10.0.22000.434; windows server 2019: v < 10.0.17763.2452; windows server 2022: v < 10.0.20348.469; windows server 20h2: v < 10.0.19042.1466
Fixed inKB5009543, KB5009545, KB5009555, KB5009557, KB5009566 (applies to 21 product versions) — build 10.0.17763.2452, 10.0.18363.2037+
Real-world incidentsWhat we've seen

CISA added this CVE to the Known Exploited Vulnerabilities catalog on 2022-02-04 based on evidence of active exploitation in the wild. Federal agencies required to remediate by 2022-02-18.

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 CatalogKB5009543

Manual remediation steps

Apply the Microsoft Security Update

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

Required KB Updates

    1
    KB5009543 — https://support.microsoft.com/help/5009543
    1
    KB5009545 — https://support.microsoft.com/help/5009545
    1
    KB5009555 — https://support.microsoft.com/help/5009555
    1
    KB5009557 — https://support.microsoft.com/help/5009557
    1
    KB5009566 — https://support.microsoft.com/help/5009566

Supersedes: KB5008206, KB5008212, KB5008215, KB5008218, KB5008223

Affected Products

    1
    Windows 10 Version 1809 for 32-bit Systems
    1
    Windows 10 Version 1809 for ARM64-based Systems
    1
    Windows 10 Version 1809 for x64-based Systems
    1
    Windows 10 Version 1909 for 32-bit Systems
    1
    Windows 10 Version 1909 for ARM64-based Systems
    1
    Windows 10 Version 1909 for x64-based Systems
    1
    Windows 10 Version 20H2 for 32-bit Systems
    1
    Windows 10 Version 20H2 for ARM64-based Systems
    1
    Windows 10 Version 21H1 for 32-bit Systems
    1
    Windows 10 Version 21H1 for ARM64-based Systems
    1
    Windows 10 Version 21H1 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 11 version 21H2 for ARM64-based Systems
    1
    Windows 11 version 21H2 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
    (…1 more product versions)

Fixed Build Numbers

    1
    10.0.17763.2452
    1
    10.0.18363.2037
    1
    10.0.19042.1466
    1
    10.0.19043.1466
    1
    10.0.19044.1466
    1
    10.0.20348.469
    1
    10.0.22000.434

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 KB5009543
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 KB5009543 for the affected products in your update management console.

Microsoft Download Center Links

    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5009543
    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5009545
    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5009555
    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5009557
    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5009566

Verification

Confirm the update is installed:

Get-HotFix | Where-Object { $_.HotFixID -in @('KB5009543','KB5009545','KB5009555','KB5009557','KB5009566') }

References

    1
    Microsoft Security Response Center: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2022-21882
    1
    KB article: https://support.microsoft.com/help/5009543
    1
    KB article: https://support.microsoft.com/help/5009545
    1
    KB article: https://support.microsoft.com/help/5009555
    1
    NVD entry: https://nvd.nist.gov/vuln/detail/CVE-2022-21882
    1
    CISA KEV: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2022-21882

Discovery Credit

RyeLv (@b2ahex), Big CJTeam of Tianfu Cup

PowerShell automationComing soon

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

References

↗ CVE-2022-21882↗ MSRC Advisory↗ NVD↗ KBKB5009543