Windows 11 gets a security fix – but it has broken some PC games

Windows 11 users are in some cases seeing a security error caused by an update to Microsoft’s built-in antivirus for the OS, and it seems to be causing havoc with certain games that use anti-cheat software (as well as other problems in general).

As Windows Latest reports, after the latest update for Microsoft Defender – one that’s pushed automatically to the app – affected users are seeing a confusing warning that states: “Kernel-mode Hardware-enforced Stack Protection is off. Your device may be vulnerable.”

Kernel-mode what now? In a nutshell, this is a freshly updated Windows 11 security feature (which was introduced with 22H2) that uses the processor to give software or games additional security (protecting the memory stack, and preventing a would-be attacker from leveraging an opportunity to run malicious code).

The warning from the Windows Security app gives the user the opportunity to toggle stack protection back on, but the problem is that if this is done, it fails to work (in some instances, anyway) – and the warning persists.

The underlying issue is an apparent driver conflict, although it would seem that in many cases, it’s anti-cheat features that are throwing a serious spanner in the works with Windows 11.

At any rate, if you try to ‘review incompatible drivers’ to resolve the issue, Windows 11 comes up with nothing in some cases – literally producing a blank panel according to one report on Reddit.

That said, another user who had a problem with Phantasy Star Online 2 found that the incompatible ‘driver’ was pointed to, and it was a file belonging to GameGuard (the anti-cheat product for that game). Uninstalling PSO2 resolved the issue, so the conflict seems to be with GameGuard.

It’s not just old titles like PSO2 that are hit by this problem, but newer games including Destiny 2 and Valorant which also employ anti-cheat systems that can be hooked deeply into the OS.

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Analysis: This one’s a bit of a head-scratcher

This looks to be a messy one, as further to issues with the error itself, we have reports of folks who can turn on the stack protection feature successfully, but it then causes crashes with some of their games (PUBG for example).

As Windows Latest notes, this security option was apparently just updated to replace Local Security Authority (LSA), which has been misfiring itself since Windows 11’s cumulative update for March 2023. LSA has been persisting in telling users that it’s turned off, when in actual fact, it isn’t.

In short, the fix for one gremlin appears to have caused more serious problems, which is not a pleasant state of affairs (though it’s nothing that we haven’t seen before with Windows, mind you).

It’s not clear exactly how widespread the new stack protection compatibility clash is, but there are already a number of reports across various online forums – and it’s not just gamers who are affected either (but games do seem to be causing a lot of the issues experienced from what we can tell at this point).

If you do find yourself coming up against this bugbear, as observed above, one route is to uninstall the offending game (with anti-cheat). Of course, that isn’t ideal, especially if it’s one of your favorites.

Some folks are managing to turn on the stack protection option successfully after encountering the error, but then some games or apps are crashing. Again, that’s hardly ideal. Or you could just leave the feature turned off, but that doesn’t seem very sensible, as you’re missing an element of (potentially important) security protection.

With no satisfying workaround yet discovered, hopefully Microsoft is investigating this one, and will come forward with some advice in short order.