Memory usage increase after applying KB5001337 Patch

Question

Hi,

We have a .Net Application which suddenly started taking about 10G to 14GB of Memory when run on Windows 10 1909 machine with KB5001337 Patch applied to it.. On uninstalling this package, we get the Memory usage by this application back to nominal amount 100 -200MB...

Looking at the Information provided by the MS website for that patch it did mention issue with Scroll bar, however I do not see any issues with our scroll bars in my application but see a huge consumption of Memory...

Scroll bar controls might appear blank on the screen and not function after installing this update. This issue affects 32-bit applications running on 64-bit Windows 10 (WOW64) that create scroll bars using a superclass of the USER32.DLL SCROLLBAR window class. This issue also affects HScrollBar and VScrollBar controls that are used in Visual Basic 6 applications and the classes derived from System.Windows.Forms.ScrollBar that are used in .NET Windows Forms applications. A memory usage increase of up to 4 GB might occur in 64-bit applications when you create a scroll bar control.
Scroll bars you create using the SCROLLBAR window class or using the WS_HSCROLL and WS_VSCROLL window styles function normally. Applications that use the scroll bar control that is implemented in COMCTL32.DLL version 6 are not affected. This includes .NET Windows Forms applications that call Application.EnableVisualStyles().
Microsoft is working on a resolution and will provide an update in an upcoming release.

So reaching out to ask if anyone else has seen any issue like this and if so is there a workaround so we do not use the updated Windows dll but an older version?

This application also works well in Windows 10 20H2 with newest patch, but only causes issue for the Windows 10 version 1909 patch of KB5001337 with hug memory consumption.

Thanks,
Ani

Answer 1

Hi Ani,
Thank you for your post and feedback.
Microsoft confirms a known issue after installing KB5001337. I also met some people have same issue. (someone has blank scroll bar or high memory).
Based on my search, for the latest security April 22, 2021—KB5001396 (OS Build 18363.1533) Preview, the issue still insists.
As the Mircrosoft website said, Microsoft is working on a resolution and will provide an update in an upcoming release.
So I suggest that we can keep the current version without installing the update for now.
As far as I know, task Manager shows you the amount of memory belonging to the application that happens to be paged into real memory at the time (the working set). This is probably what you're seeing. Sometimes we could manually reduce app's working set by using the Win32 API.
I think that's what Microsoft is doing right now, including modify some related DLLs, so I recommend waiting for the next update and fix.
Hope this helps and please help to accept as Answer if the response is useful.
Best Regards,
Carl