Noticed your C drive filling up even though you haven’t installed anything new? You’re probably not imagining it. Microsoft has quietly confirmed a bug that can chew through as much as 500GB of storage, and most people have no clue it’s happening until their drive is nearly full.
Okay, But What’s Actually Filling It Up?
Turns out there’s a single file behind all this: CapabilityAccessManager.db-wal. Basically, whenever an app asks to use your camera, mic, location, or screen recording, Windows jots that down somewhere, and this is where it lands.
Most of the time you’d never even know it exists, since it usually sits at a couple megabytes and minds its own business. But on some PCs, it seems to have forgotten how to clean up after itself, so every single permission check just piles onto the same file instead of getting cleared out. Leave a machine running long enough with this happening in the background, and 60GB turns into 100GB, and in the worst cases people have found it sitting north of 500GB.
Nobody really catches this early, and honestly, it’s hard to blame them for that.
Pop open Windows’ storage settings expecting an answer, and you won’t get one. It just shows “System files” ballooning in size with absolutely no indication of why. Try to go digging for the file yourself through File Explorer, and Windows practically slams the door on you with an “Access denied” message.
If you’re trying to figure out whether this has hit your machine, you don’t really need any special tools for it, though something like WizTree does make the visual side of things easier. The quicker route is this:
- Head to Settings > Storage > Show more categories > System & reserved, then look at System files.
- If that figure looks way bigger than it has any business being, you’re probably dealing with this exact bug.
- To be extra sure, fire up Command Prompt with admin rights and paste this in:
robocopy "C:\ProgramData\Microsoft\Windows\CapabilityAccessManager" "%TEMP%\CAMCheck" /L /B /R:0 /W:0 /BYTES /NP
The good news is Microsoft already has a fix out. It landed inside KB5095093, an optional update from late June 2026, and it basically retrains the database to stop hoarding logs the way it has been. Grab it now through Windows Update > Advanced options > Optional updates if you’re impatient. If not, it’ll show up on its own once July’s Patch Tuesday rolls around.
One thing though, don’t go trying to delete that file yourself or shut off the service running it. Microsoft’s flagged that as a bad idea, since it tends to come right back anyway, and messing with it manually can open the door to other problems.
Best bet for now? Install the update and let it sort itself out.
