Exchange Server SE SU9 has been released

Hi All,

Last Week, Microsoft has released the Exchange SE SU9. I was in Holidays so i’ve installed it today.

• Exchange Team Blog Released: July 2026 Exchange Server Security Updates
• Description of the security update for Microsoft Exchange Server Subscription Edition RTM: August 11, 2026 (KB5121573)

It fixes the following CVEs

• CVE-2026-62910 - Microsoft Common Vulnerabilities and Exposures
• CVE-2026-62911 - Microsoft Common Vulnerabilities and Exposures
• CVE-2026-62912 - Microsoft Common Vulnerabilities and Exposures
• CVE-2026-62913 - Microsoft Common Vulnerabilities and Exposures
• CVE-2026-65813 - Microsoft Common Vulnerabilities and Exposures
• CVE-2026-62914 - Microsoft Common Vulnerabilities and Exposures
• CVE-2026-62915 - Microsoft Common Vulnerabilities and Exposures

Known isssues

• Wrapper messages appear in shared mailbox in hybrid environments after installing the June 2026 Security Update
• Published calendar (.ics) returns HTTP 500 for calendar applications
• Availability (free/busy) fails for delegated mailboxes in Exchange hybrid deployments using Graph API only

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 SU9 (KB5121573)

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

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

There are now some legacy Security Groups that can be deleted

• Exchange Domain Servers
• Exchange Enterprise Servers
• Exchange Recipient Administrators

Happy Exchange patching 😎

Regards
Andres Bohren