Sysadmin shock as Windows Server 2025 installs itself after update labeling error
Administrators are reporting unexpected appearances of Windows Server 2025 after what was published as a security update turned out to be a complete operating system upgrade.
The problem was flagged by a customer of web app security biz Heimdal. Arriving at the office on the morning of November 5, they found, to their horror, that every Windows Server 2022 system had either upgraded itself to Windows Server 2025 or was about to.
Sysadmins are cautious by nature, so an unplanned operating system upgrade could easily result in morning coffee being sprayed over a keyboard.
Heimdal's services include patch management, and it relies on Microsoft to label patches accurately to ensure the correct update is applied to the correct software at the correct time. In this instance, what should have been a security update turned out to be Windows Server 2025.
It took Heimdal a while to trace the problem. According to a post on Reddit: "Due to the limited initial footprint, identifying the root cause took some time. By 18:05 UTC, we traced the issue to the Windows Update API, where Microsoft had mistakenly labeled the Windows Server 2025 upgrade as KB5044284."
