KB5078775 ESU for Windows Server 2012

KB5078775 is the ESU Monthly Rollup Update for Windows Server 2012. It was released on 10 March 2026 under the ‘Patch Tuesday’ program.

Salient points

• KB5078775 supersedes KB5075971 released in February 2026.
• KB5078775 corresponds to Windows Server 2012 build version 6.2.9200.25973.
• KB5078775 requires the KB5079234 Servicing Stack Update to be installed prior to installing the main monthly rollup update.
• Without the installation of KB5079234, the ESU KB5078775 cannot be installed. For WSUS administrators, KB5079234 needs to be approved before KB5078775 will be fetched and deployed automatically.
• If you install language pack after installing KB5078775, you would need to reinstall the security update. All language pack installations must be completed before installing the monthly rollup update on Windows Server 2012.
• KB5078775 is an Extended Security Update. A valid subscription key to the ESU program is required before installing the monthly rollup update.
• Windows Server 2012 is impacted by 31 security vulnerabilities reported in March 2026 security bulletin.
• No zero-day vulnerabilities have been disclosed for Windows Server 2012 and Windows Server 2012 Server Core installation in March security bulletin.
• The latest cumulative update for Internet Explorer 11 on Windows Server 2012 continues to be KB5066840 released in October 2025. So, new update for Internet Explorer is not needed in March 2026.

Servicing Stack Update KB5079234

The Servicing Stack Update for Windows Server 2012 for March 2026 is KB5079234. It corresponds to KB5078775 ESU.

For automated deployments of KB5078775 through the Windows Update program, the Servicing Stack Update KB5079234 is offered for installation as part of the installation process of the monthly rollup update KB5078775.

• Download KB5079234 from the Microsoft Update Catalog page – 9.8 MB

The Servicing Stack Update file is a small file around 10 MB size Upon installation, it would not cause server reboot.

Once the SSU is installed, you can proceed with the installation of the main monthly rollup update KB5078775.

Download KB5078775

You can download the monthly rollup update KB5078775 for Windows Server 2012 from the Windows Update Catalog page shared below:

• Download KB5078775 from the Microsoft Update Catalog page (450.7 MB)

We would reiterate that you need a valid ESU program subscription before you could install the ESU KB5078775 on Windows Server 2012.

Zero-day Vulnerabilities

No new zero-day security vulnerability has been reported for Windows Server 2012 and Windows Server 2012 Server Core installation in February month’s security bulletin released by Microsoft on 10 Mar 2026.

Internet Explorer Cumulative Update – KB5066840

To secure the Windows Server 2012, you also need to patch Internet Explorer 11 with the latest cumulative update. KB5066840 is the cumulative update for Internet Explorer released on 14 October 2025. No new security update for Internet Explorer 11 was released in November 2025.

You can download the IE Cumulative Update for Windows Server 2012 from the link shared below:

Download Cumulative Update for Internet Explorer – KB5066840 (54.9 MB)

KB5078775 – Changelog

Since this is an ESU, the focus remains on securing the Windows Server 2012 deployments. The following changes have been reported for KB5078775:

• [Internal Windows OS] Miscellaneous security improvements were made to internal Windows OS functionality.