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

KB5070879: Windows Server 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 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 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
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↗ NVD↗ KBKB5070879