IRONSMITHINTEL
CRITICALCVSS9.8
|
Actively Exploited
|CISA KEV|CVE-2023-29357|Auth: none — unauthenticated|Reboot: required|Manual only

KB5002402: Windows Server Security Update (June 2023)

Microsoft SharePoint Server contains an unspecified vulnerability that allows an unauthenticated attacker, who has gained access to spoofed JWT authentication tokens, to use them for executing a network attack. This attack bypasses authentication, enabling the attacker to gain administrator privileges.

Published Jun 14, 2023 · 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. CISA has confirmed use of this vulnerability in known ransomware campaigns — treat as high priority for remediation. Federal agencies are required to remediate by 2024-01-31 under CISA BOD 22-01.

How the attack worksNo clicks needed

This is a Software Vulnerability (CWE-303) (CWE-303) vulnerability in Microsoft SharePoint Server. 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:

●SharePoint Administrators
●IT Security
●Running sharepoint server: 2019
Fixed inKB5002402, KB5002403 (applies to 1 product version) — build 16.0.10399.20005
Real-world incidentsWhat we've seen

CISA confirms this CVE has been used in known ransomware campaigns. Added to the KEV catalog on 2024-01-10; federal agencies required to remediate by 2024-01-31.

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 CatalogKB5002402

Manual remediation steps

Apply the Microsoft Security Update

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

Required KB Updates

    1
    KB5002402 — https://support.microsoft.com/help/5002402
    1
    KB5002403 — https://support.microsoft.com/help/5002403

Supersedes: KB5002330, KB5002389

Affected Products

    1
    Microsoft SharePoint Server 2019

Fixed Build Numbers

    1
    16.0.10399.20005

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 KB5002402
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 KB5002402 for the affected products in your update management console.

Microsoft Download Center Links

    1
    https://www.microsoft.com/download/details.aspx?familyid=254d91bb-b6b7-4668-b1c1-0045f769ba14
    1
    https://www.microsoft.com/download/details.aspx?familyid=ce540046-c17e-4999-9015-a7c0c4b345fd

Verification

Confirm the update is installed:

Get-HotFix | Where-Object { $_.HotFixID -in @('KB5002402','KB5002403') }

References

    1
    Microsoft Security Response Center: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-29357
    1
    KB article: https://support.microsoft.com/help/5002402
    1
    KB article: https://support.microsoft.com/help/5002403
    1
    NVD entry: https://nvd.nist.gov/vuln/detail/CVE-2023-29357
    1
    CISA KEV: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-29357

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-2023-29357↗ MSRC Advisory↗ NVD↗ KBKB5002402