The Vmwp.exe process on a Hyper-V host leaks memory in Windows 8 or Windows Server 2012

Applies to: Windows 8 EnterpriseWindows Server 2012 R2 Foundation


Consider the following scenario:
  • You run Windows 8 or Windows Server 2012 as a Hyper-V host.
  • You set up a Windows 7 guest virtual machine within the Hyper-V host.
  • You install a third-party management console on the Windows 7 guest virtual machine.

In this scenario, the memory heap for this virtual machine worker process (Vmwp.exe) on the Hyper-V host leaks memory and may cause system instability.


This problem occurs because the read buffer is not freed correctly.


Hotfix information

A supported hotfix is available from Microsoft Support. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing the problem described in this article. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, go to the following Microsoft website: Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.


To apply this hotfix, you must have Windows 8 or Windows Server 2012 installed.

Restart requirement

You do not have to restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any previously released hotfix.


Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.


See the terminology Microsoft uses to describe software updates for more information.