IRONSMITHINTEL
HIGHCVSS7.8
|
Actively Exploited
|CISA KEV|CVE-2023-23376|Auth: low — authenticated user|Reboot: required|Manual only

KB5022834: Windows Server Security Update (February 2023)

Microsoft Windows Common Log File System (CLFS) driver contains an unspecified vulnerability that allows for privilege escalation.

Published Feb 14, 2023 · Updated May 16, 2026
Why patchRisk explained in plain English
Worst-case scenarioIf unpatched

A local 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 2023-03-07 under CISA BOD 22-01.

How the attack worksNo clicks needed

This is a Heap-based Buffer Overflow (CWE-122) vulnerability in Microsoft Windows. Windows Common Log File System Driver Elevation of Privilege Vulnerability Exploitation requires local access, low attack complexity, a low-privilege authenticated account, and no user interaction required.

Am I affected?Quick check

Probably yes if any of these apply:

●Windows Administrators
●Systems Engineers
●IT Security
●Running windows 10 1507: v < 10.0.10240.19747; windows 10 1607: v < 10.0.14393.5717; windows 10 1809: v < 10.0.17763.4010; windows 10 20h2: v < 10.0.19042.2604; windows 10 21h2: v < 10.0.19044.2604; windows 10 22h2: v < 10.0.19045.2604; windows 11 21h2: v < 10.0.22000.1574; windows 11 22h2: v < 10.0.22621.1265; windows server 2008: -, r2; windows server 2012: -, r2; windows server 2016: v < 10.0.14393.5717; windows server 2019: v < 10.0.17763.4010; windows server 2022: v < 10.0.20348.1540
Fixed inKB5022834, KB5022836, KB5022838, KB5022840, KB5022842, KB5022845, KB5022858, KB5022872, KB5022874, KB5022890, KB5022893, KB5022894, KB5022895, KB5022899, KB5022903, KB5022921 (applies to 35 product versions) — build 10.0.10240.19747, 10.0.14393.5717+
Real-world incidentsWhat we've seen

CISA confirms this CVE has been used in known ransomware campaigns. Added to the KEV catalog on 2023-02-14; federal agencies required to remediate by 2023-03-07.

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 CatalogKB5022834

Manual remediation steps

Apply the Microsoft Security Update

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

Required KB Updates

    1
    KB5022834 — https://support.microsoft.com/help/5022834
    1
    KB5022836 — https://support.microsoft.com/help/5022836
    1
    KB5022838 — https://support.microsoft.com/help/5022838
    1
    KB5022840 — https://support.microsoft.com/help/5022840
    1
    KB5022842 — https://support.microsoft.com/help/5022842
    1
    KB5022845 — https://support.microsoft.com/help/5022845
    1
    KB5022858 — https://support.microsoft.com/help/5022858
    1
    KB5022872 — https://support.microsoft.com/help/5022872
    1
    KB5022874 — https://support.microsoft.com/help/5022874
    1
    KB5022890 — https://support.microsoft.com/help/5022890
    1
    KB5022893 — https://support.microsoft.com/help/5022893
    1
    KB5022894 — https://support.microsoft.com/help/5022894
    1
    KB5022895 — https://support.microsoft.com/help/5022895
    1
    KB5022899 — https://support.microsoft.com/help/5022899
    1
    KB5022903 — https://support.microsoft.com/help/5022903
    1
    KB5022921 — https://support.microsoft.com/help/5022921

Supersedes: KB5022282, KB5022286, KB5022287, KB5022289, KB5022291, KB5022297, KB5022303, KB5022338, KB5022340, KB5022348, KB5022352

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 ARM64-based Systems
    1
    Windows 10 Version 1809 for x64-based Systems
    1
    Windows 10 Version 20H2 for 32-bit Systems
    1
    Windows 10 Version 20H2 for ARM64-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 10 for 32-bit Systems
    1
    Windows 10 for x64-based Systems
    1
    Windows 11 Version 22H2 for ARM64-based Systems
    1
    Windows 11 Version 22H2 for x64-based Systems
    1
    Windows 11 version 21H2 for ARM64-based Systems
    1
    Windows 11 version 21H2 for x64-based Systems
    1
    Windows Server 2008 R2 for x64-based Systems Service Pack 1
    1
    (…15 more product versions)

Fixed Build Numbers

    1
    10.0.10240.19747
    1
    10.0.14393.5717
    1
    10.0.17763.4010
    1
    10.0.19042.2604
    1
    10.0.19044.2604
    1
    10.0.19045.2604
    1
    10.0.20348.1540
    1
    10.0.20348.1547
    1
    10.0.22621.1265
    1
    10.0.22621.1574
    1
    (…4 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 KB5022834
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 KB5022834 for the affected products in your update management console.

Microsoft Download Center Links

    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5022834
    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5022836
    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5022838
    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5022840
    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5022842
    1
    (…10 more)

Verification

Confirm the update is installed:

Get-HotFix | Where-Object { $_.HotFixID -in @('KB5022834','KB5022836','KB5022838','KB5022840','KB5022842','KB5022845','KB5022858','KB5022872','KB5022874','KB5022890','KB5022893','KB5022894','KB5022895','KB5022899','KB5022903','KB5022921') }

References

    1
    Microsoft Security Response Center: https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2023-23376
    1
    KB article: https://support.microsoft.com/help/5022834
    1
    KB article: https://support.microsoft.com/help/5022840
    1
    KB article: https://support.microsoft.com/help/5022842
    1
    NVD entry: https://nvd.nist.gov/vuln/detail/CVE-2023-23376
    1
    CISA KEV: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-23376

Discovery Credit

Microsoft Threat Intelligence Center (MSTIC) Microsoft Security Response Center (MSRC)

PowerShell automationComing soon

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

References

↗ CVE-2023-23376↗ MSRC Advisory↗ NVD↗ KBKB5022834