Don’t delete that mysterious ‘inetpub’ Windows folder, says Microsoft, as it’s supposedly important for system security

The internet was mystified earlier this month by… okay, let me start this again. Very specific parts of the internet were mystified earlier this month by an empty folder labelled “inetpub” turning up among system files after the Windows 11 April 2025 Update.

Some took to deleting it, which on the surface caused no issues at all. However, Microsoft has now updated a support document instructing users to leave it alone, as it’s tied to a security update.

The inetpub folder is used to store and manage Internet Information Services (ISS) logs, but even users who did not have the service enabled saw it appear after the KB5055523 Windows update (via Windows Central). There it sat, as if it had always been there, but curious users were left none the wiser as to why it blinked into existence on their machines.

Microsoft has now confirmed in an updated support document for vulnerability CVE-2025-21204 that the folder is part of “changes that increase protection” and that “this folder should not be deleted regardless of whether Internet Information Services (IIS) is active on the target device.”

The text is highlighted in bold, so you know it’s serious. However, Microsoft has still not explained why the empty folder is so vital to its security fixes, leaving us no more enlightened as to what it actually does.

CVE-2025-21204 is related to an elevation of privilege vulnerability that allows would-be-attackers to modify system files and folders, so perhaps MS is adding the folder to all installs whether it’s needed or not to create a standardised system that is less vulnerable to this particular exploit.

Pure speculation, that. I honestly have no idea, and Microsoft doesn’t seem to feel the need to explain any further. A folder it is, and a folder it must remain.

Microsoft has reportedly told Windows Central that Windows 11 users who deleted the folder must reinstate it by turning Internet Information Services on in the Control Panel. Then the folder can go back to doing… whatever it’s supposed to do, I presume.

The mystery continues. I for one shall be keeping an eye on my personal intepub folder to see if it does anything interesting, like populating itself with logs of my recent spelling mistakes or keeping track of my shopping habits. You never know, do you?