IRONSMITHINTEL
MEDIUMCVSS6.5
|
Actively Exploited
|CISA KEV|CVE-2026-32201|Auth: none — unauthenticated|Reboot: required|Manual only

KB5002853: Windows Server Security Update (April 2026)

Microsoft SharePoint Server contains an improper input validation vulnerability that allows an unauthorized attacker to perform spoofing over a network.

Published Apr 14, 2026 · Updated May 16, 2026
Why patchRisk explained in plain English
Worst-case scenarioIf unpatched

A remote attacker, without authentication, can achieve partial data exposure, partial data tampering. Federal agencies are required to remediate by 2026-04-28 under CISA BOD 22-01.

How the attack worksNo clicks needed

This is a Improper Input Validation (CWE-20) vulnerability in Microsoft SharePoint Server. Improper input validation in Microsoft Office SharePoint allows an unauthorized attacker to perform spoofing over a network. Exploitation requires remote network access, low attack complexity, no authentication required, and no user interaction required.

📧

Phishing link

→

🖼

Malicious file

🔓

Server compromised

Am I affected?Quick check

Probably yes if any of these apply:

●SharePoint Administrators
●IT Security
●Running sharepoint server: v < 16.0.19725.20210, 2016, 2019
Fixed inKB5002853, KB5002854, KB5002861 (applies to 3 product versions) — build 16.0.10417.20114, 16.0.19725.20210+
Real-world incidentsWhat we've seen

CISA added this CVE to the Known Exploited Vulnerabilities catalog on 2026-04-14 based on evidence of active exploitation in the wild. Federal agencies required to remediate by 2026-04-28.

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 CatalogKB5002853

Manual remediation steps

Apply the Microsoft Security Update

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

Required KB Updates

    1
    KB5002853 — https://support.microsoft.com/help/5002853
    1
    KB5002854 — https://support.microsoft.com/help/5002854
    1
    KB5002861 — https://support.microsoft.com/help/5002861

Supersedes: KB5002843, KB5002845, KB5002850

Affected Products

    1
    Microsoft SharePoint Enterprise Server 2016
    1
    Microsoft SharePoint Server 2019
    1
    Microsoft SharePoint Server Subscription Edition

Fixed Build Numbers

    1
    16.0.10417.20114
    1
    16.0.19725.20210
    1
    16.0.5548.1003

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 (may or may not be required for this update)

Microsoft Update Catalog (manual download)

1
Open https://catalog.update.microsoft.com
2
Search for KB5002853
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 KB5002853 for the affected products in your update management console.

Microsoft Download Center Links

    1
    https://www.microsoft.com/en-us/download/details.aspx?id=108607
    1
    https://www.microsoft.com/en-us/download/details.aspx?id=108608
    1
    https://www.microsoft.com/en-us/download/details.aspx?id=108611

Verification

Confirm the update is installed:

Get-HotFix | Where-Object { $_.HotFixID -in @('KB5002853','KB5002854','KB5002861') }

References

    1
    Microsoft Security Response Center: https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2026-32201
    1
    KB article: https://support.microsoft.com/help/5002853
    1
    KB article: https://support.microsoft.com/help/5002854
    1
    KB article: https://support.microsoft.com/help/5002861
    1
    NVD entry: https://nvd.nist.gov/vuln/detail/CVE-2026-32201
    1
    CISA KEV: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-32201

Discovery Credit

Microsoft

PowerShell automationComing soon

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

References

↗ CVE-2026-32201↗ MSRC Advisory↗ NVD↗ KBKB5002853