IRONSMITHINTEL
HIGHCVSS8.8
|
Actively Exploited
|CISA KEV|CVE-2026-21510|Auth: none — unauthenticated|Reboot: required|Manual only

KB5075897: Windows Server Security Update (February 2026)

Microsoft Windows Shell contains a protection mechanism failure vulnerability that could allow an unauthorized attacker to bypass a security feature over a network.

Published Feb 10, 2026 · Updated May 16, 2026
Why patchRisk explained in plain English
Worst-case scenarioIf unpatched

A remote attacker, without authentication, can achieve full data confidentiality loss, arbitrary modification of data, complete denial of service or system unavailability. Federal agencies are required to remediate by 2026-03-03 under CISA BOD 22-01.

How the attack worksNo clicks needed

This is a Software Vulnerability (CWE-693) (CWE-693) vulnerability in Microsoft Windows. Protection mechanism failure in Windows Shell allows an unauthorized attacker to bypass a security feature over a network. Exploitation requires remote network access, low attack complexity, no authentication required, and user interaction required.

📧

Phishing link

→

🖼

Malicious file

🔓

Server compromised

Am I affected?Quick check

Probably yes if any of these apply:

●Windows Administrators
●Systems Engineers
●IT Security
●Running windows 10 1607: v < 10.0.14393.8868; windows 10 1809: v < 10.0.17763.8389; windows 10 21h2: v < 10.0.19044.6937; windows 10 22h2: v < 10.0.19045.6937; windows 11 23h2: v < 10.0.22631.6649; windows 11 24h2: v < 10.0.26100.7781; windows 11 25h2: v < 10.0.26200.7781; windows server 2012: -, r2; windows server 2016: v < 10.0.14393.8868; windows server 2019: v < 10.0.17763.8389; windows server 2022: v < 10.0.20348.4711; windows server 2022 23h2: v < 10.0.25398.2149; windows server 2025: v < 10.0.26100.32313
Fixed inKB5075897, KB5075899, KB5075904, KB5075906, KB5075912, KB5075941, KB5075942, KB5075943, KB5075970, KB5075971, KB5075999, KB5077179, KB5077181, KB5077212 (applies to 31 product versions) — build 10.0.14393.8868, 10.0.17763.8389+
Real-world incidentsWhat we've seen

CISA added this CVE to the Known Exploited Vulnerabilities catalog on 2026-02-10 based on evidence of active exploitation in the wild. Federal agencies required to remediate by 2026-03-03.

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 CatalogKB5075897

Manual remediation steps

Apply the Microsoft Security Update

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

Required KB Updates

    1
    KB5075897 — https://support.microsoft.com/help/5075897
    1
    KB5075899 — https://support.microsoft.com/help/5075899
    1
    KB5075904 — https://support.microsoft.com/help/5075904
    1
    KB5075906 — https://support.microsoft.com/help/5075906
    1
    KB5075912 — https://support.microsoft.com/help/5075912
    1
    KB5075941 — https://support.microsoft.com/help/5075941
    1
    KB5075942 — https://support.microsoft.com/help/5075942
    1
    KB5075943 — https://support.microsoft.com/help/5075943
    1
    KB5075970 — https://support.microsoft.com/help/5075970
    1
    KB5075971 — https://support.microsoft.com/help/5075971
    1
    KB5075999 — https://support.microsoft.com/help/5075999
    1
    KB5077179 — https://support.microsoft.com/help/5077179
    1
    KB5077181 — https://support.microsoft.com/help/5077181
    1
    KB5077212 — https://support.microsoft.com/help/5077212

Supersedes: KB5073379, KB5073450, KB5073455, KB5073457, KB5073696, KB5073698, KB5073724, KB5074109

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 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 11 Version 26H1 for ARM64-based Systems
    1
    Windows 11 version 26H1 for x64-based Systems
    1
    Windows Server 2012
    1
    Windows Server 2012 (Server Core installation)
    1
    (…11 more product versions)

Fixed Build Numbers

    1
    10.0.14393.8868
    1
    10.0.17763.8389
    1
    10.0.19044.6937
    1
    10.0.19045.6937
    1
    10.0.20348.4711
    1
    10.0.20348.4773
    1
    10.0.22631.6649
    1
    10.0.25398.2149
    1
    10.0.26100.32313
    1
    10.0.26100.32370
    1
    (…7 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 KB5075897
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 KB5075897 for the affected products in your update management console.

Microsoft Download Center Links

    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5075897
    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5075899
    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5075904
    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5075906
    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5075912
    1
    (…9 more)

Verification

Confirm the update is installed:

Get-HotFix | Where-Object { $_.HotFixID -in @('KB5075897','KB5075899','KB5075904','KB5075906','KB5075912','KB5075941','KB5075942','KB5075943','KB5075970','KB5075971','KB5075999','KB5077179','KB5077181','KB5077212') }

References

    1
    Microsoft Security Response Center: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21510
    1
    KB article: https://support.microsoft.com/help/5075897
    1
    KB article: https://support.microsoft.com/help/5075899
    1
    KB article: https://support.microsoft.com/help/5075904
    1
    NVD entry: https://nvd.nist.gov/vuln/detail/CVE-2026-21510
    1
    CISA KEV: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-21510

Discovery Credit

Anonymous, Google Threat Intelligence Group, Microsoft Threat Intelligence Center (MSTIC), Microsoft Security Response Center (MSRC), and Office Product Group Security Team

PowerShell automationComing soon

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

References

↗ CVE-2026-21510↗ MSRC Advisory↗ NVD↗ KBKB5075897