Description of the Security Only update for .NET Framework 4.6, 4.6.1, 4.6.2, 4.7, and 4.7.1 for Windows Server 2012 (KB 4096235)


Summary


This update resolves a vulnerability in Microsoft .NET Framework that could cause denial of service when .NET Framework and .NET core components process XML documents incorrectly. An attacker who has successfully exploited this vulnerability could cause a denial of service against a .NET Framework application. To learn more about this vulnerability, see Microsoft Common Vulnerabilities and Exposures CVE-2018-0765.

Additionally, this update resolves a security feature bypass vulnerability in Windows that could allow an attacker to bypass Device Guard. An attacker who successfully exploits this vulnerability could circumvent a User Mode Code Integrity (UMCI) policy on the computer. To learn more about this vulnerability, see Microsoft Common Vulnerabilities and Exposures CVE-2018-1039.

Important

  • All updates for .NET Framework 4.6, 4.6.1, 4.6.2, 4.7, and 4.7.1 require the d3dcompiler_47.dll to be installed. We recommend that you install the included d3dcompiler_47.dll before you apply this update. For more information about the d3dcompiler_47.dll, see KB 4019990.
  • 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.

Quality and reliability improvements


CLR1

  • Fixed a floating-point overflow in the thread pool’s hill climbing algorithm.
  • When you observe high CPU usage by ntoskrnl!KiPageFault that originates from BGC (as indicated by the clr!*gc_heap::bgc_thread_function), you might want this change so that the GC no longer uses the OS-implemented GetWriteWatch function to track BGC heap modifications. That process is very expensive because each of these page faults must take a process-wide lock. This is especially noticeable in the recent versions of the OS. You are probably seeing that most of the CPU is spent in the ntoskrnl!ExpWaitForSpinLockExclusiveAndAcquire function. This fix makes GC use CLR’s own implementation of the GetWriteWatch function instead.

1 Common Language Runtime (CLR)

Additional information about this security update


For more information about this security update as it relates to Windows Server 2012, see the following article in the Microsoft Knowledge Base:

4099638 Security Only update for .NET Framework 3.5 SP1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, and 4.7.1 updates for Windows Server 2012 (KB 4099638)

How to obtain and install the update


Method 1: Microsoft Update Catalog

To get the stand-alone package for this update, go to the Microsoft Update Catalog.
 

Method 2: Windows Software Update Services (WSUS)

On your WSUS server, follow these steps:

  1. Click Start, click Administrative Tools, and then click Microsoft Windows Server Update Services 3.0.
  2. Expand ComputerName, and then click Action.
  3. Click Import Updates.
  4. WSUS opens a browser window in which you may be prompted to install an ActiveX control. You must install the ActiveX control to continue.
  5. After the control is installed, you see the Microsoft Update Catalog screen. Enter 4099638 into the Search box, and then click Search.
  6. Locate the .NET Framework packages that match the operating systems, languages, and processors in your environment. Click Add to add them to your basket.
  7. After you select all the packages that you need, click View Basket.
  8. To import the packages to your WSUS server, click Import.
  9. After the packages are imported, click Close to return to WSUS.

The updates are now available for installation through WSUS.

Update deployment information

For deployment details for this security update, go to the following article in the Microsoft Knowledge Base:

20180508 Security update deployment information: May 8, 2018

Update removal information

Note We do not recommend that you remove any security update. To remove this update, use the Programs and Features item in Control Panel.

Update restart information

This update does not require a system restart after you apply it unless files that are being updated are locked or are being used.

Update replacement information

This update does not replace any previously released update.

File information



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 the times for these files are listed in Coordinated Universal Time (UTC). The dates and the times for these files on your local computer are displayed in your local time together with your current daylight saving time (DST) bias. Additionally, the dates and the times may change when you perform certain operations on the files.

Windows Server 2012 file information

How to obtain help and support for this security update