This security update resolves a vulnerability in the Microsoft .NET Framework that could allow remote code execution when Microsoft .NET Framework processes untrusted input. An attacker who successfully exploited this vulnerability in software by using the .NET Framework could take control of an affected system. An 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 validates untrusted input. To learn more about this vulnerability, see Microsoft Common Vulnerabilities and Exposures CVE-2017-8759.
- All updates for .NET Framework 4.6, 4.6.1, 4.6.2, and 4.7 require the d3dcompiler_47.dll update to be 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.
- 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 fixes
- A fix included in the May Monthly Security and Quality Rollup is being changed to improve the performance of network latency about Active Directory lookups for enhanced key usage (EKU) object identifiers (OIDs) function that is used in TLS (Transport Layer Security) and SSL (Secure Sockets Layer) certificates.
- Under certain circumstances, Windows Presentation Framework (WPF) applications (notably, Visual Studio) are observed to consume disproportionate amount of CPU cycles in relation to their actual workload. Frequently, these applications eventually crash. This is seen in WPF applications that are left running in a locked logon session, or when they are left running in a disconnected Terminal Services session.
- Under certain circumstances, the JIT compiler can perform an incorrect common subexpression elimination (CSE) optimization which results in an incorrect value being computed.
- For certain XslCompiledTransform objects, the JIT compiler can perform an incorrect tail call optimization.
- When you run certain large server workloads, the JIT compiler can cause an Access Violation and causes early termination of the common language runtime (CLR).
- When Windows Forms controls are anchored to the right edge (a nondefault anchor style value), in PerMonitor DPI aware application, anchoring distance is scaled incorrectly on each scaling pass. You may see that controls are moving toward the right edge of the window on each scaling pass and eventually disappear, or that controls are stretched incorrectly.
- Applications that run on the .NET Framework do not respect the settings that are specified in the registry for AppContext switches. Regardless of the registry option setting for an AppContext flag, the application behaves as if the value specified is set to "false."
Known issues in this update
- After you install the September 12, 2017, .NET Security and Quality Rollups that apply to the .NET Framework 4.6, 4.6.1, 4.6.2, and 4.7, you experience rendering issues in Windows Presentation Foundation (WPF) applications that use WPF types in a Windows service. For more information, see KB 4043601.
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:
4041083 Security and Quality Rollup for the .NET Framework 3.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2 and 4.7 updates for Windows 7 SP1 and Windows Server 2008 R2 SP1: September 12, 2017
For more information about this security update as it relates to Windows Server 2008 Service Pack 2 (SP2), see the following article in the Microsoft Knowledge Base:
4041086 Security and Quality Rollup for the .NET Framework 2.0 SP2, 4.5.2, 4.6, 4.6.1, 4.6.2 and 4.7 updates for Windows Server 2008 SP2: September 12, 2017
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 get security updates automatically, see Windows Update: FAQ.
Method 2: 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 4041083.
- For Windows Server 2008 R2 SP1, go to 4041086.
Method 3: Windows Software Update Services (WSUS)
On your WSUS server, follow these steps:
- Click Start, click Administrative Tools, and then click Microsoft Windows Server Update Services 3.0.
- Expand ComputerName, and then click Action.
- Click Import Updates.
- WSUS will open a browser window in which you may be prompted to install an ActiveX control. You must install the ActiveX control to continue.
- Once the control is installed, you will see the Microsoft Update Catalog screen. Enter 4041083 for Windows 7 SP1 and Windows Server 2008 R2 SP1 or enter 4041086 for Windows Server 2008 SP2 into the Search box, and then click Search.
- Locate the .NET Framework packages that match the operating systems, languages, and processors in your environment. Click Add to add them to your basket.
- When you have selected all the packages you need, click View Basket.
- Click Import to import the packages to your WSUS server.
- Click Close once the packages have been imported 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:
20170912 Security update deployment information: September 12, 2017
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
How to obtain help and support for this security update
- Help for installing updates: Windows Update FAQ
- Security solutions for IT professionals: TechNet Security Support and Troubleshooting
- Help for protecting your Windows-based products and services from viruses and malware: Microsoft Secure
- Local support according to your country: International Support