KB5071503 is the ESU Monthly Rollup Update for Windows Server 2012 R2. It was released on 9 December 2025 under the ‘Patch Tuesday’ program.
Salient points
- KB5071503 supersedes KB5068905 released in November 2025.
- KB5071503 corresponds to server build number 6.3.9600.22920.
- KB5071503 requires a Servicing Stack Update to be installed prior to installing the main monthly rollup update. KB5068783 is the SSU corresponding to KB5071503. This SSU was released in November 2025. If you applied the November security update on Windows Server 2012 R2, the SSU or Servicing Stack Update would be already there on the server.
- If you install language pack after installing KB5071503, you would need to reinstall the security update once again. All language pack installations must be completed before installing the monthly rollup update on Windows Server 2012 R2.
- KB5071503 is an Extended Security Update. A valid subscription key to the ESU program is required before installing the monthly rollup update.
- In December, Microsoft released information about 57 security vulnerabilities across all products.
- Windows Server 2012 R2 is impacted by 12 security vulnerabilities reported in December 2025 security bulletin. One of these vulnerabilities is a ‘CRITICAL’ severity vulnerability.
- Two zero-day vulnerabilities affect Windows Server 2012 R2 and Windows Server 2012 R2 Server Core installation.
- Meanwhile, the last cumulative update for Internet Explorer on Windows Server 2012 R2 was last released in October 2025 (KB5066840)
Servicing Stack Update KB5068783
The Servicing Stack Update for Windows Server 2012 R2 for November and December is KB5058783. It corresponds to KB5068905 ESU and KB5071503.
For automated deployments of KB5071503 through the Windows Update program, the Servicing Stack Update KB5068783 is offered for installation as part of the installation process of the monthly rollup update KB5068905. No further action is needed to install KB5068783 for automated installations of KB5071503.
WSUS administrators need to authorize or approve KB5068783 before KB5071503 is fetched and installed in WSUS.
If you choose to deploy KB5071503 manually, you need to download and install KB5068783 on the Windows Server 2012 R2.
The Servicing Stack Update file is a small file of 10.6 MB. 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 KB5071503.
Download KB5071503
You can download the monthly rollup update KB5071503 for Windows Server 2012 R2 from the Windows Update Catalog page shared below:
We would reiterate that you need a valid ESU program subscription before you could install the ESU KB5071503 on Windows Server 2012 R2.
Zero-day Vulnerabilities
One zero-day vulnerability affects Windows Server 2012 R2 and Windows Server 2012 R2 Server Core installation, as per the latest security reported released by Microsoft on 9 December 2025.
The zero-day vulnerabilities are shared below:
| CVE Details | CVSS Score | Comments |
|---|---|---|
| CVE-2025-54100 | 7.8 | Remote Code Execution Vulnerability in PowerShell (Windows) |
KB5071503 – Changelog
Since this is an ESU, the focus remains on securing the Windows Server 2012 R2 deployments. The following changes have been reported for KB5071503:
- [Internal Windows OS] Miscellaneous security improvements were made to internal Windows OS functionality.
- [PowerShell 5.1] The Invoke-WebRequest command now includes a confirmation prompt with a security warning of a script execution risk. You can choose to continue or cancel the request. For additional details, see CVE-2025-54100 and KB5074596: PowerShell 5.1: Preventing script execution from web content.
Internet Explorer Cumulative Update – KB5066840
To secure the Windows Server 2012 R2, 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 IE update has been released in November or December 2025.
You can download the IE Cumulative Update for Windows Server 2012 R2 from the link shared below:
Download Cumulative Update for Internet Explorer – KB5066840 (54.9 MB)
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