IRONSMITHINTEL
CRITICALCVSS9.8
|
Actively Exploited
|CISA KEV|CVE-2025-59287|Auth: none — unauthenticated|Reboot: required|Manual only

KB5070879: Windows Server 2019 / 2022 / 2025 +more Security Update (October 2025)

Microsoft Windows Server Update Service (WSUS) contains a deserialization of untrusted data vulnerability that allows for remote code execution.

Published Oct 14, 2025 · Updated Jun 10, 2026
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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 2025-11-14 under CISA BOD 22-01.

How the attack worksNo clicks needed

This is a Deserialization of Untrusted Data (CWE-502) vulnerability in Microsoft Windows. Deserialization of untrusted data in Windows Server Update Service allows an unauthorized attacker to execute code 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:

●Windows Administrators
●Systems Engineers
●IT Security
●Running windows server 2012: -, r2; windows server 2016: v < 10.0.14393.8524; windows server 2019: v < 10.0.17763.7922; windows server 2022: v < 10.0.20348.4297; windows server 2022 23h2: v < 10.0.25398.1916; windows server 2025: v < 10.0.26100.6905

Affected OS versions

Windows Server 2019Windows Server 2022Windows Server 2025Windows Server 2016Windows Server 2012 R2
Fixed inKB5070879, KB5070881, KB5070882, KB5070883, KB5070884, KB5070886, KB5070887, KB5070892, KB5070893 (applies to 13 product versions) — build 10.0.14393.8524, 10.0.17763.7922+
Real-world incidentsWhat we've seen

Active exploitation documented in the wild. Threat-research write-up: https://hawktrace.com/blog/CVE-2025-59287

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 CatalogKB5070879

Manual remediation steps

Apply the Microsoft Security Update

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

Required KB Updates

    1
    KB5070879 — https://support.microsoft.com/help/5070879
    1
    KB5070881 — https://support.microsoft.com/help/5070881
    1
    KB5070882 — https://support.microsoft.com/help/5070882
    1
    KB5070883 — https://support.microsoft.com/help/5070883
    1
    KB5070884 — https://support.microsoft.com/help/5070884
    1
    KB5070886 — https://support.microsoft.com/help/5070886
    1
    KB5070887 — https://support.microsoft.com/help/5070887
    1
    KB5070892 — https://support.microsoft.com/help/5070892
    1
    KB5070893 — https://support.microsoft.com/help/5070893

Affected Products

    1
    Windows Server 2012
    1
    Windows Server 2012 (Server Core installation)
    1
    Windows Server 2012 R2
    1
    Windows Server 2012 R2 (Server Core installation)
    1
    Windows Server 2016
    1
    Windows Server 2016 (Server Core installation)
    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
    Windows Server 2025 (Server Core installation)

Fixed Build Numbers

    1
    10.0.14393.8524
    1
    10.0.17763.7922
    1
    10.0.20348.4297
    1
    10.0.25398.1916
    1
    10.0.26100.6905
    1
    6.2.9200.25728
    1
    6.3.9600.22826

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 KB5070879
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 KB5070879 for the affected products in your update management console.

Microsoft Download Center Links

    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5070879
    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5070881
    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5070882
    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5070883
    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5070884
    1
    (…2 more)

Verification

Confirm the update is installed:

Get-HotFix | Where-Object { $_.HotFixID -in @('KB5070879','KB5070881','KB5070882','KB5070883','KB5070884','KB5070886','KB5070887','KB5070892','KB5070893') }

References

    1
    Microsoft Security Response Center: https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2025-59287
    1
    KB article: https://support.microsoft.com/help/5070879
    1
    KB article: https://support.microsoft.com/help/5070881
    1
    KB article: https://support.microsoft.com/help/5070882
    1
    NVD entry: https://nvd.nist.gov/vuln/detail/CVE-2025-59287
    1
    CISA KEV: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-59287

Discovery Credit

Markus Wulftange with CODE WHITE GmbH, MEOW, f7d8c52bec79e42795cf15888b85cbad

PowerShell automationComing soon

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

References

↗ CVE-2025-59287↗ MSRC Advisory↗ KBKB5070879

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