MS15-042: Vulnerability in Windows Hyper-V could allow denial of service: April 14, 2015

Applies to: Windows Server 2012 R2 DatacenterWindows Server 2012 R2 StandardWindows Server 2012 R2 Essentials


This security update resolves a vulnerability in Microsoft Windows. The vulnerability could allow denial of service if an authenticated attacker runs a specially crafted application in a virtual machine (VM) session. Notice that the denial of service does not allow an attacker to execute code or elevate user rights on other VMs that are running on the Hyper-V host. However, the issue could cause other VMs on the host not to be manageable in Virtual Machine Manager.


Microsoft has released security bulletin MS15-042. To learn more about this security bulletin:

How to obtain help and support for this security update

Help installing updates:
Support for Microsoft Update

Security solutions for IT professionals:
TechNet Security Troubleshooting and Support

Help protect your Windows-based computer from viruses and malware:
Virus Solution and Security Center

Local support according to your country:
International Support

More Information

Known issues in this security update

  • After you install this security update, you may find that old file location cleanup operations are affected when you run a storage migration of Cluster Shared Volume (CSV). To resolve this issue, install vmms.exe version 6.3.9600.17787, included in update 3037313. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
    3037313 Old files are not removed after a migration of virtual machine storage in Windows 8.1 or Windows Server 2012 R2

File information

The English (United States) version of this software update installs files that have the attributes that are listed in the following tables. The dates and times for these files are listed in Coordinated Universal Time (UTC). The dates and times for these files on your local computer are displayed in your local time and with your current daylight saving time (DST) bias. Additionally, the dates and times may change when you perform certain operations on the files.