Microsoft has issued a warning to anyone who deleted a ‘mystery’ folder that appeared following the latest Windows 11 update.
The tech giant sparked confusion among its users last week as the latest version of Windows was released.
However, when Microsoft fans installed the update, they were surprised to find an unexpected empty folder was added too.
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And while many assumed it was an error and deleted the folder, the firm has now revealed the reasoning behind it and why it shouldn’t be erased.
This is because the folder was put there intentionally to fix a bug that enables attackers to modify files and folders in a system.
Speaking to Windows Latest, Microsoft shared that the folder is a security patch for the bug titled CVE-2025-21204.
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In its advisory, the tech firm said: “The CVE-2025-21204 security flaw is caused by an improper link resolution issue before file access (‘link following’) in the Windows Update Stack which likely means that, on unpatched devices, Windows Update may follow symbolic links in a way that can let local attackers trick the system into accessing or modifying unintended files or folders.”
Microsoft continued: “On unpatched devices, Windows Update may follow symbolic links in a way that can let local attackers trick the system into accessing or modifying unintended files or folders.”
The company added: “This folder should not be deleted regardless of whether Internet Information Services (IIS) is active on the target device. This behaviour is part of changes that increase protection and does not require any action from IT admins and end users.”
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However, if you are someone who deleted the folder before its reasoning became clear, don’t fret, because Microsoft has explained how to restore it.
How can you restore the Windows 11 folder?
First, you’ll need to head to System Settings and turn on Internet Information System (IIS).
After this, type ‘control panel’ on your PC and open up the app.
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From there, select Programs followed by ‘turn Windows features on and off’.
This will bring you to a dialog box which you can scroll down to find Internet Information Services. Hit the box next to this option and click ‘OK’.
Once this is done, the folder should reappear.
The firm has emphasized the importance of restoring the folder if you have deleted it because it is a vital security patch to block attackers from modifying anything in your PC’s system.