Exchange Server SE SU12 has been released

Hi All,

Yesterday, Microsoft has released the Exchange SE SU11.

• Exchange Team Blog Released: November 2026 Exchange Server Security Updates
• Description of the security update for Microsoft Exchange Server Subscription Edition RTM November 10, 2026 (KB5133453)

It fixes the following CVEs

• CVE-2026-118149 - Microsoft Exchange Server Remote Code Execution Vulnerability
• CVE-2026-118150 - Microsoft Exchange Server Elevation of Privilege Vulnerability
• CVE-2026-118151 - Microsoft Exchange Server Elevation of Privilege Vulnerability
• CVE-2026-118152 - Microsoft Exchange Server Spoofing Vulnerability
• CVE-2026-118153 - Microsoft Exchange Server Denial of Service Vulnerability
• CVE-2026-118154 - Microsoft Exchange Server Elevation of Privilege Vulnerability
• CVE-2026-118157 - Microsoft Exchange Server Elevation of Privilege Vulnerability
• CVE-2026-118207 - Microsoft Exchange Server Remote Code Execution Vulnerability
• CVE-2026-118208 - Microsoft Exchange Server Spoofing Vulnerability

Issues resolved in this update

• Microsoft graph displays incorrect free/busy availability information in Microsoft Exchange server SE hybrid setup

The Process is simple: Install the SU and the run the Exchange Health Checker

You can download the Security Update here:

• Download Security Update for Exchange Server SE RTM SU12 (KB5133453)

Installation

Bevore starting the Installation, i check if there is a pending reboot with a PowerShell Script i’ve wrote

• Check for pending reboot with PowerShell

.\Check-PendingReboot.ps1

After a reboot everything looks fine

.\Check-PendingReboot.ps1

Let’s start the Installation

The Installation of the Security Update has successfully completed

Check the Version

Get-Command Exsetup.exe | ForEach-Object {$_.FileVersionInfo}

Check for Pending reboot

.\Check-PendingReboot.ps1

Healthchecker

Microsoft recommends to run the HealthChecker after each Installation. The HealthChecker can be downloaded here:

• HealthChecker

In the first run, the HealthChecker updates the Script

.\HealthChecker.ps1

Now we can run the HealthChecker - nothing worring was found

.\HealthChecker.ps1

Happy Exchange patching 😎

Regards
Andres Bohren