IRONSMITHINTEL
HIGHCVSS7.5
|
Actively Exploited
|CISA KEV|CVE-2021-42287|Auth: low — authenticated user|Reboot: required|Manual only

KB5007186: Windows Server Security Update (November 2021)

Microsoft Active Directory Domain Services contains an unspecified vulnerability that allows for privilege escalation.

Published Nov 10, 2021 · Updated May 16, 2026
Why patchRisk explained in plain English
Worst-case scenarioIf unpatched

A remote attacker, with a low-privilege account, can achieve full data confidentiality loss, arbitrary modification of data, complete denial of service or system unavailability. CISA has confirmed use of this vulnerability in known ransomware campaigns — treat as high priority for remediation. Federal agencies are required to remediate by 2022-05-02 under CISA BOD 22-01.

How the attack worksNo clicks needed

This vulnerability affects Microsoft Active Directory. Active Directory Domain Services Elevation of Privilege Vulnerability Exploitation requires remote network 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:

●IT Security
●Running windows server 2008: -, r2; windows server 2012: -, r2; windows server 2016: v < 10.0.14393.4770, 2004; windows server 2019: v < 10.0.17763.2300; windows server 2022: v < 10.0.20348.350
Fixed inKB5007186, KB5007192, KB5007205, KB5007206, KB5007233, KB5007236, KB5007245, KB5007246, KB5007247, KB5007255, KB5007260, KB5007263 (applies to 18 product versions) — build 10.0.14393.4770, 10.0.17763.2300+
Real-world incidentsWhat we've seen

CISA confirms this CVE has been used in known ransomware campaigns. Added to the KEV catalog on 2022-04-11; federal agencies required to remediate by 2022-05-02.

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 CatalogKB5007186

Manual remediation steps

Apply the Microsoft Security Update

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

Required KB Updates

    1
    KB5007186 — https://support.microsoft.com/help/5007186
    1
    KB5007192 — https://support.microsoft.com/help/5007192
    1
    KB5007205 — https://support.microsoft.com/help/5007205
    1
    KB5007206 — https://support.microsoft.com/help/5007206
    1
    KB5007233 — https://support.microsoft.com/help/5007233
    1
    KB5007236 — https://support.microsoft.com/help/5007236
    1
    KB5007245 — https://support.microsoft.com/help/5007245
    1
    KB5007246 — https://support.microsoft.com/help/5007246
    1
    KB5007247 — https://support.microsoft.com/help/5007247
    1
    KB5007255 — https://support.microsoft.com/help/5007255
    1
    KB5007260 — https://support.microsoft.com/help/5007260
    1
    KB5007263 — https://support.microsoft.com/help/5007263

Supersedes: KB5006669, KB5006670, KB5006672, KB5006699, KB5006714, KB5006736, KB5006739, KB5006743

Affected Products

    1
    Windows Server 2008 R2 for x64-based Systems Service Pack 1
    1
    Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation)
    1
    Windows Server 2008 for 32-bit Systems Service Pack 2
    1
    Windows Server 2008 for 32-bit Systems Service Pack 2 (Server Core installation)
    1
    Windows Server 2008 for x64-based Systems Service Pack 2
    1
    Windows Server 2008 for x64-based Systems Service Pack 2 (Server Core installation)
    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, version 2004 (Server Core installation)
    1
    Windows Server, version 20H2 (Server Core Installation)

Fixed Build Numbers

    1
    10.0.14393.4770
    1
    10.0.17763.2300
    1
    10.0.19041.1348
    1
    10.0.20348.350
    1
    6.0.6003.21282
    1
    6.1.7601.25769
    1
    6.2.9200.23517
    1
    6.3.9600.20174

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 KB5007186
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 KB5007186 for the affected products in your update management console.

Microsoft Download Center Links

    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5007186
    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5007192
    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5007205
    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5007206
    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5007233
    1
    (…7 more)

Verification

Confirm the update is installed:

Get-HotFix | Where-Object { $_.HotFixID -in @('KB5007186','KB5007192','KB5007205','KB5007206','KB5007233','KB5007236','KB5007245','KB5007246','KB5007247','KB5007255','KB5007260','KB5007263') }

References

    1
    Microsoft Security Response Center: https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-42287
    1
    KB article: https://support.microsoft.com/help/5007186
    1
    KB article: https://support.microsoft.com/help/5007192
    1
    KB article: https://support.microsoft.com/help/5007205
    1
    NVD entry: https://nvd.nist.gov/vuln/detail/CVE-2021-42287
    1
    CISA KEV: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-42287

Discovery Credit

Andrew Bartlett of Catalyst IT

PowerShell automationComing soon

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

References

↗ CVE-2021-42287↗ MSRC Advisory↗ NVD↗ KBKB5007186