IRONSMITHINTEL
CRITICALCVSS9.8
|
Actively Exploited
|CISA KEV|CVE-2024-21410|Auth: none — unauthenticated|Reboot: required|Manual only

KB5035606: Windows Server Security Update (February 2024)

Microsoft Exchange Server contains an unspecified vulnerability that allows for privilege escalation.

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 full data confidentiality loss, arbitrary modification of data, complete denial of service or system unavailability. Federal agencies are required to remediate by 2024-03-07 under CISA BOD 22-01.

How the attack worksNo clicks needed

This is a Improper Authentication (CWE-287) vulnerability in Microsoft Exchange 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:

●Exchange Administrators
●Messaging Team
●IT Security
●Running exchange server: 2016, 2019
Fixed inKB5035606, KB5036386 (applies to 3 product versions) — build 15.01.2507.037, 15.2.1544.004
Real-world incidentsWhat we've seen

CISA added this CVE to the Known Exploited Vulnerabilities catalog on 2024-02-15 based on evidence of active exploitation in the wild. Federal agencies required to remediate by 2024-03-07.

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 CatalogKB5035606

Manual remediation steps

Apply the Microsoft Security Update

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

Required KB Updates

    1
    KB5035606 — https://support.microsoft.com/help/5035606
    1
    KB5036386 — https://support.microsoft.com/help/5036386

Supersedes: KB5030877

Affected Products

    1
    Microsoft Exchange Server 2016 Cumulative Update 23
    1
    Microsoft Exchange Server 2019 Cumulative Update 13
    1
    Microsoft Exchange Server 2019 Cumulative Update 14

Fixed Build Numbers

    1
    15.01.2507.037
    1
    15.2.1544.004

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 KB5035606
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 KB5035606 for the affected products in your update management console.

Microsoft Download Center Links

    1
    https://www.microsoft.com/download/details.aspx?familyID=9fbd842e-828a-408a-b562-5632a8a827ab
    1
    https://www.microsoft.com/download/details.aspx?familyid=348cb3fe-a4fb-45aa-b6d0-51b72e1712b1

Verification

Confirm the update is installed:

Get-HotFix | Where-Object { $_.HotFixID -in @('KB5035606','KB5036386') }

References

    1
    Microsoft Security Response Center: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2024-21410
    1
    KB article: https://support.microsoft.com/help/5035606
    1
    KB article: https://support.microsoft.com/help/5036386
    1
    NVD entry: https://nvd.nist.gov/vuln/detail/CVE-2024-21410
    1
    CISA KEV: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2024-21410

Discovery Credit

Internally found by Microsoft

PowerShell automationComing soon

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

References

↗ CVE-2024-21410↗ MSRC Advisory↗ NVD↗ KBKB5035606