IRONSMITHINTEL
HIGHCVSS7.6
|
Actively Exploited
|CISA KEV|CVE-2024-21351|Auth: none — unauthenticated|Reboot: required|Manual only

KB5034763: Windows Server Security Update (February 2024)

Microsoft Windows SmartScreen contains a security feature bypass vulnerability that allows an attacker to bypass the SmartScreen user experience and inject code to potentially gain code execution, which could lead to some data exposure, lack of system availability, or both.

Published Feb 13, 2024 · Updated May 16, 2026
Why patchRisk explained in plain English
Worst-case scenarioIf unpatched

A remote attacker, without authentication, can achieve partial data exposure, arbitrary modification of data, partial service disruption. Federal agencies are required to remediate by 2024-03-05 under CISA BOD 22-01.

How the attack worksNo clicks needed

This is a Code Injection (CWE-94) vulnerability in Microsoft Windows. Windows SmartScreen Security Feature Bypass Vulnerability Exploitation requires remote network access, low attack complexity, no authentication required, and 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 10 1507: v < 10.0.10240.20469; windows 10 1607: v < 10.0.14393.6709; windows 10 1809: v < 10.0.17763.5458; windows 10 21h2: v < 10.0.19044.4046; windows 10 22h2: v < 10.0.19045.4046; windows 11 21h2: v < 10.0.22000.2777; windows 11 22h2: v < 10.0.22621.3155; windows 11 23h2: v < 10.0.22631.3155; windows server 2016: -; windows server 2019: v < 10.0.17763.5458; windows server 2022: v < 10.0.20348.2322; windows server 2022 23h2: v < 10.0.25398.709
Fixed inKB5034763, KB5034765, KB5034766, KB5034767, KB5034768, KB5034770, KB5034774 (applies to 22 product versions) — build 10.0.10240.20469, 10.0.14393.6709+
Real-world incidentsWhat we've seen

CISA added this CVE to the Known Exploited Vulnerabilities catalog on 2024-02-13 based on evidence of active exploitation in the wild. Federal agencies required to remediate by 2024-03-05.

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 CatalogKB5034763

Manual remediation steps

Apply the Microsoft Security Update

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

Required KB Updates

    1
    KB5034763 — https://support.microsoft.com/help/5034763
    1
    KB5034765 — https://support.microsoft.com/help/5034765
    1
    KB5034766 — https://support.microsoft.com/help/5034766
    1
    KB5034767 — https://support.microsoft.com/help/5034767
    1
    KB5034768 — https://support.microsoft.com/help/5034768
    1
    KB5034770 — https://support.microsoft.com/help/5034770
    1
    KB5034774 — https://support.microsoft.com/help/5034774

Supersedes: KB5034119, KB5034121, KB5034122, KB5034123, KB5034127, KB5034129, KB5034134

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 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 23H2 for ARM64-based Systems
    1
    Windows 11 Version 23H2 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 2016
    1
    (…2 more product versions)

Fixed Build Numbers

    1
    10.0.10240.20469
    1
    10.0.14393.6709
    1
    10.0.17763.5458
    1
    10.0.19044.4046
    1
    10.0.19045.4046
    1
    10.0.20348.2322
    1
    10.0.22000.2777
    1
    10.0.22621.3155
    1
    10.0.22631.3155

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 KB5034763
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 KB5034763 for the affected products in your update management console.

Microsoft Download Center Links

    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5034763
    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5034765
    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5034766
    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5034767
    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5034768
    1
    (…2 more)

Verification

Confirm the update is installed:

Get-HotFix | Where-Object { $_.HotFixID -in @('KB5034763','KB5034765','KB5034766','KB5034767','KB5034768','KB5034770','KB5034774') }

References

    1
    Microsoft Security Response Center: https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2024-21351
    1
    KB article: https://support.microsoft.com/help/5034763
    1
    KB article: https://support.microsoft.com/help/5034765
    1
    KB article: https://support.microsoft.com/help/5034766
    1
    NVD entry: https://nvd.nist.gov/vuln/detail/CVE-2024-21351
    1
    CISA KEV: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2024-21351

Discovery Credit

Eric Lawrence with Microsoft

PowerShell automationComing soon

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

References

↗ CVE-2024-21351↗ MSRC Advisory↗ NVD↗ KBKB5034763