Description of the Security Only update for .NET Framework 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, and 4.7.2 for Windows 7 SP1 and Server 2008 R2 SP1 and for .NET Framework 4.6 for Server 2008 SP2 (KB 4457027)

Summary

This security update resolves a vulnerability in Microsoft .NET Framework that could allow remote code execution when .NET Framework processes untrusted input. An attacker who successfully exploits this vulnerability in software by using .NET Framework could take control of an affected system. The attacker could then install programs; view, change, or delete data; or create new accounts that have full user rights. Users whose accounts are configured to have fewer user rights on the system could be less affected than users who operate with administrative user rights.

To exploit the vulnerability, an attacker would first have to convince the user to open a malicious document or application.

This security update addresses the vulnerability by correcting how .NET Framework validates untrusted input.

To learn more about this vulnerability, see Microsoft Common Vulnerabilities and Exposures CVE-2018-8421.

Important

All updates for .NET Framework 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, and 4.7.2 require that the d3dcompiler_47.dll update is installed. We recommend that you install the included d3dcompiler_47.dll update before you apply this update. For more information about the d3dcompiler_47.dll update, see KB 4019990 for Windows 7 SP1 and Windows Server 2008 R2 SP1. Or, see KB 4019478 for Windows Server 2008 Service Pack 2 (SP2).
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.

Additional information about this security update

For more information about this security update as it relates to Windows 7 Service Pack 1 (SP1) and Windows Server 2008 R2 SP1, see the following article in the Microsoft Knowledge Base:

4457914 Security Only updates for .NET Framework 3.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, and 4.7.2 for Windows 7 SP1 and Server 2008 R2 SP2 (KB 4457914)

For more information about this security update as it relates to Windows Server 2008 SP2, see the following article in the Microsoft Knowledge Base:

4457917 Security Only updates for .NET Framework 2.0 SP2, 3.0 SP2, 4.5.2, and 4.6 for Windows Server 2008 SP2 (KB 4457917)

Known issues

After the September 2018 .NET Framework security update is applied to resolve CVE-2018-8421 (.NET Framework remote code execution vulnerability), SharePoint out-of-the-box workflows stop working.

For more information about this known issue, see the following article in the Microsoft Knowledge Base:

4465015 SharePoint Workflows stop working after you install .NET security updates for CVE-2018-8421

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.

For Windows 7 SP1 and Windows Server 2008 R2 SP1, go to update KB 4457914.
For Windows Server 2008 SP2, go to update KB 4457917.

Method 2: Windows Software Update Services (WSUS)

On your WSUS server, follow these steps:

Select Start, select Administrative Tools, and then select Microsoft Windows Server Update Services 3.0.
Expand ComputerName, and then select Action.
Select Import Updates.
WSUS opens a browser window in which you may be prompted to install an ActiveX control. Install the ActiveX control to continue.
After the ActiveX control is installed, you see the Microsoft Update Catalog screen. Type 4457915 in the Search box, and then select Search.
Locate the .NET Framework packages that match the operating systems, languages, and processors in your environment. Select Add to add them to your basket.
After you select all the packages that you need, select View Basket.
To import the packages to your WSUS server, select Import.
After the packages are imported, select 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:

20180911 Security update deployment information: September 11, 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 hash

File name	SHA1 hash	SHA256 hash
NDP46-KB4457027-x86.exe	8295ADD8DCAD0A178D8C91EF038ABFE1F70CD030	531D260D69D0CADF8E33532C949FF65D7A09269F435AF0178F40B8509240F64B
NDP46-KB4457027-x64.exe	D41E8CFE75D2D0EF99F9E1FD8C75DB343027CBF0	93B86AFAFDF1AF20323A3487673451191274D59D06D498362AA38E4C04B4D81A

File attributes for all supported x86-based systems

The English (United States) version of this 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 together with your current daylight saving time (DST) bias. Additionally, the dates and times may change when you perform certain operations on the files.

File name	File version	File size	Date	Time
System.Workflow.Activities.dll	4.7.3180.0	1,054,216	09-Aug-2018	22:06
System.Workflow.ComponentModel.dll	4.7.3180.0	1,547,288	09-Aug-2018	22:06
System.Workflow.Runtime.dll	4.7.3180.0	501,752	09-Aug-2018	22:06
WorkflowServiceHostPerformanceCounters.dll	4.7.3180.0	92,216	09-Aug-2018	22:05

File attributes for all supported x64-based systems