IRONSMITHINTEL
HIGHCVSS7.0
|
Actively Exploited
|CISA KEV|CVE-2023-28229|Auth: low — authenticated user|Reboot: required|Manual only

KB5025221: Windows Server Security Update (April 2023)

Microsoft Windows Cryptographic Next Generation (CNG) Key Isolation Service contains an unspecified vulnerability that allows an attacker to gain specific limited SYSTEM privileges.

Published Apr 11, 2023 · 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 2023-10-25 under CISA BOD 22-01.

How the attack worksNo clicks needed

This is a Software Vulnerability (CWE-591) (CWE-591) vulnerability in Microsoft Windows CNG Key Isolation Service. Windows CNG Key Isolation Service Elevation of Privilege Vulnerability 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:

●Windows Administrators
●Systems Engineers
●IT Security
●Running windows 10 1507: v < 10.0.10240.19869; windows 10 1607: v < 10.0.14393.5850; windows 10 1809: v < 10.0.17763.4252; windows 10 20h2: v < 10.0.19042.2846; windows 10 21h2: v < 10.0.19044.2846; windows 10 22h2: v < 10.0.19045.2846; windows 11 21h2: v < 10.0.22000.1817; windows 11 22h2: v < 10.0.22621.1555; windows server 2008: -, r2; windows server 2012: -, r2; windows server 2016: -; windows server 2019: -; windows server 2022: -
Fixed inKB5025221, KB5025224, KB5025228, KB5025229, KB5025230, KB5025234, KB5025239, KB5025271, KB5025272, KB5025273, KB5025277, KB5025279, KB5025285, KB5025287, KB5025288 (applies to 35 product versions) — build 10.0.10240.19869, 10.0.14393.5850+
Real-world incidentsWhat we've seen

CISA added this CVE to the Known Exploited Vulnerabilities catalog on 2023-10-04 based on evidence of active exploitation in the wild. Federal agencies required to remediate by 2023-10-25.

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 CatalogKB5025221

Manual remediation steps

Apply the Microsoft Security Update

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

Required KB Updates

    1
    KB5025221 — https://support.microsoft.com/help/5025221
    1
    KB5025224 — https://support.microsoft.com/help/5025224
    1
    KB5025228 — https://support.microsoft.com/help/5025228
    1
    KB5025229 — https://support.microsoft.com/help/5025229
    1
    KB5025230 — https://support.microsoft.com/help/5025230
    1
    KB5025234 — https://support.microsoft.com/help/5025234
    1
    KB5025239 — https://support.microsoft.com/help/5025239
    1
    KB5025271 — https://support.microsoft.com/help/5025271
    1
    KB5025272 — https://support.microsoft.com/help/5025272
    1
    KB5025273 — https://support.microsoft.com/help/5025273
    1
    KB5025277 — https://support.microsoft.com/help/5025277
    1
    KB5025279 — https://support.microsoft.com/help/5025279
    1
    KB5025285 — https://support.microsoft.com/help/5025285
    1
    KB5025287 — https://support.microsoft.com/help/5025287
    1
    KB5025288 — https://support.microsoft.com/help/5025288

Supersedes: KB5023696, KB5023697, KB5023698, KB5023702, KB5023705, KB5023706, KB5023713, KB5023755, KB5023765, KB5023769

Affected Products

    1
    Windows 10 Version 1607 for 32-bit Systems
    1
    Windows 10 Version 1607 for x64-based Systems
    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 20H2 for 32-bit Systems
    1
    Windows 10 Version 20H2 for ARM64-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 10 for 32-bit Systems
    1
    Windows 10 for x64-based Systems
    1
    Windows 11 Version 22H2 for ARM64-based Systems
    1
    Windows 11 Version 22H2 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 2008 R2 for x64-based Systems Service Pack 1
    1
    (…15 more product versions)

Fixed Build Numbers

    1
    10.0.10240.19869
    1
    10.0.14393.5850
    1
    10.0.17763.4252
    1
    10.0.19042.2846
    1
    10.0.19044.2846
    1
    10.0.19045.2846
    1
    10.0.20348.1668
    1
    10.0.22000.1817
    1
    10.0.22621.1555
    1
    6.0.6003.22015
    1
    (…3 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 KB5025221
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 KB5025221 for the affected products in your update management console.

Microsoft Download Center Links

    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5025221
    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5025224
    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5025228
    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5025229
    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5025230
    1
    (…10 more)

Verification

Confirm the update is installed:

Get-HotFix | Where-Object { $_.HotFixID -in @('KB5025221','KB5025224','KB5025228','KB5025229','KB5025230','KB5025234','KB5025239','KB5025271','KB5025272','KB5025273','KB5025277','KB5025279','KB5025285','KB5025287','KB5025288') }

References

    1
    Microsoft Security Response Center: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-28229
    1
    KB article: https://support.microsoft.com/help/5025221
    1
    KB article: https://support.microsoft.com/help/5025224
    1
    KB article: https://support.microsoft.com/help/5025229
    1
    NVD entry: https://nvd.nist.gov/vuln/detail/CVE-2023-28229
    1
    CISA KEV: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-28229

Discovery Credit

k0shl of Kunlun Lab

PowerShell automationComing soon

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

References

↗ CVE-2023-28229↗ MSRC Advisory↗ NVD↗ KBKB5025221