IRONSMITHINTEL
HIGHCVSS7.2
|
Actively Exploited
|CISA KEV|CVE-2023-24955|Auth: high — administrative privileges|Reboot: required|Manual only

KB5002389: Windows Server Security Update (May 2023)

Microsoft SharePoint Server contains a code injection vulnerability that allows an authenticated attacker with Site Owner privileges to execute code remotely.

Published May 9, 2023 · Updated May 16, 2026
Why patchRisk explained in plain English
Worst-case scenarioIf unpatched

A remote attacker, with administrative privileges, 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 2024-04-16 under CISA BOD 22-01.

How the attack worksNo clicks needed

This is a Code Injection (CWE-94) vulnerability in Microsoft SharePoint Server. Exploitation requires remote network access, low attack complexity, an administrative account, and no user interaction required.

Am I affected?Quick check

Probably yes if any of these apply:

●SharePoint Administrators
●IT Security
●Running sharepoint enterprise server: 2016; sharepoint server: -, 2019
Fixed inKB5002389, KB5002390, KB5002397 (applies to 3 product versions) — build 16.0.10398.20000, 16.0.16130.20420+
Real-world incidentsWhat we've seen

CISA confirms this CVE has been used in known ransomware campaigns. Added to the KEV catalog on 2024-03-26; federal agencies required to remediate by 2024-04-16.

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 CatalogKB5002389

Manual remediation steps

Apply the Microsoft Security Update

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

Required KB Updates

    1
    KB5002389 — https://support.microsoft.com/help/5002389
    1
    KB5002390 — https://support.microsoft.com/help/5002390
    1
    KB5002397 — https://support.microsoft.com/help/5002397

Supersedes: KB5002373, KB5002375, KB5002385

Affected Products

    1
    Microsoft SharePoint Enterprise Server 2016
    1
    Microsoft SharePoint Server 2019
    1
    Microsoft SharePoint Server Subscription Edition

Fixed Build Numbers

    1
    16.0.10398.20000
    1
    16.0.16130.20420
    1
    16.0.5395.1000

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 KB5002389
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 KB5002389 for the affected products in your update management console.

Microsoft Download Center Links

    1
    https://www.microsoft.com/download/details.aspx?familyid=1aac4804-a1a0-4d40-8d9a-a1ac25def0b0
    1
    https://www.microsoft.com/download/details.aspx?familyid=7a299fb3-33f2-4417-809d-7bf31da6d14e
    1
    https://www.microsoft.com/download/details.aspx?familyid=c9190144-e85b-4ded-9b6f-cc9b295054f3

Verification

Confirm the update is installed:

Get-HotFix | Where-Object { $_.HotFixID -in @('KB5002389','KB5002390','KB5002397') }

References

    1
    Microsoft Security Response Center: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-24955
    1
    KB article: https://support.microsoft.com/help/5002389
    1
    KB article: https://support.microsoft.com/help/5002390
    1
    KB article: https://support.microsoft.com/help/5002397
    1
    NVD entry: https://nvd.nist.gov/vuln/detail/CVE-2023-24955
    1
    CISA KEV: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-24955

Discovery Credit

Jang (Nguyễn Tiến Giang) of StarLabs SG working with Trend Micro Zero Day Initiative

PowerShell automationComing soon

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

References

↗ CVE-2023-24955↗ MSRC Advisory↗ NVD↗ KBKB5002389