Summary
This security update resolves a vulnerability in Windows that could allow security feature bypass if an attacker runs a specially crafted application that could cause Windows Hyper-V to apply access control list (ACL) configuration settings incorrectly. Customers who do not have the Hyper-V role enabled are not affected.
To learn more about the vulnerability, see Microsoft Security Bulletin MS15-105.
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Important
- All future security and nonsecurity updates for Windows 8.1 and Windows Server 2012 R2 require update 2919355 to be installed. We recommend that you install update 2919355 on your Windows 8.1-based or Windows Server 2012 R2-based computer so that you receive future updates.
- If you install a language pack after you install this update, you must reinstall this update. Therefore, we recommend that you install any language packs that you need before you install this update. For more information, see Add language packs to Windows.
How to obtain and install the update
Method 1: Windows Update
This update is available through Windows Update. When you turn on automatic updating, this update will be downloaded and installed automatically. For more information about how to turn on automatic updating, see
Get security updates automatically.
Method 2: Microsoft Download Center
You can obtain the stand-alone update package through the Microsoft Download Center. Follow the installation instructions on the download page to install the update.
Click the download link in Microsoft Security Bulletin MS15-105 that corresponds to the version of Windows that you are running.
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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.
Windows 8.1 and Windows Server 2012 R2 file information
The files that apply to a specific product, milestone (RTM,SPn), and service branch (LDR, GDR) can be identified by examining the file version numbers as shown in the following table:
Version Product Milestone Service branch 6.3.920 0.16 xxx Windows 8.1 and Windows Server 2012 R2 RTM GDR GDR service branches contain only those fixes that are widely released to address widespread, critical issues. LDR service branches contain hotfixes in addition to widely released fixes.
Note The MANIFEST files (.manifest) and MUM files (.mum) that are installed are not listed.
For all supported x64-based versions of Windows 8.1 and Windows Server 2012 R2
| File name | File version | File size | Date | Time | Platform |
|---|---|---|---|---|---|
| Vmsif.dll | 6.3.9600.17396 | 65,024 | 08-Oct-2014 | 05:53 | x64 |
| Vmsnetsetupplugin.dll | 6.3.9600.17396 | 33,792 | 08-Oct-2014 | 06:07 | x64 |
| Vmswitch.sys | 6.3.9600.18005 | 689,152 | 05-Aug-2015 | 14:14 | x64 |
| Vmsif.dll | 6.3.9600.17396 | 65,024 | 08-Oct-2014 | 05:53 | x64 |
| Vmsntfy.dll | 6.3.9600.17396 | 91,648 | 08-Oct-2014 | 06:54 | x64 |
| Vmswitch.sys | 6.3.9600.18005 | 689,152 | 05-Aug-2015 | 14:14 | x64 |
| Vmsif.dll | 6.3.9600.17396 | 65,024 | 08-Oct-2014 | 05:53 | x64 |
| Vmsntfy.dll | 6.3.9600.17396 | 91,648 | 08-Oct-2014 | 06:54 | x64 |
| Vmswitch.sys | 6.3.9600.18005 | 689,152 | 05-Aug-2015 | 14:14 | x64 |
| Vmsif.dll | 6.3.9600.17396 | 65,024 | 08-Oct-2014 | 05:53 | x64 |
| Vmsntfy.dll | 6.3.9600.17396 | 91,648 | 08-Oct-2014 | 06:54 | x64 |
| Vmswitch.sys | 6.3.9600.18005 | 689,152 | 05-Aug-2015 | 14:14 | x64 |
How to obtain help and support for this security update
Help for installing updates: Support for Microsoft Update
Security solutions for IT professionals: TechNet Security Troubleshooting and Support
Help for protecting your Windows-based computer from viruses and malware: Virus Solution and Security Center
Local support according to your country: International Support