Security and Quality Rollup updates for .NET Framework 3.5, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, and 4.7.2 for Windows 8.1, RT 8.1 and Server 2012 R2 (KB 4471989)

**Applies to:**Microsoft .NET Framework 3.5, Microsoft .NET Framework 4.5.2, Microsoft .NET Framework 4.6, Microsoft .NET Framework 4.6.1, Microsoft .NET Framework 4.6.2, Microsoft .NET Framework 4.7, Microsoft .NET Framework 4.7.1, Microsoft .NET Framework 4.7.2

Summary

This security update resolves a vulnerability in Microsoft .NET Framework that could allow remote code execution when Microsoft .NET Framework doesn’t validate input correctly. An attacker who successfully exploits this vulnerability could take control of an affected system. The attacker could then install programs; view, change, or delete data; or create new accounts that use full user rights. Users whose accounts are configured to have fewer user rights on the system could be less affected than users who are granted administrative user rights.To exploit the vulnerability, an attacker has to pass specific input to an application that uses susceptible .NET Framework methods.This security update addresses the vulnerability by correcting how .NET Framework validates input.To learn more about this vulnerability, see Microsoft Common Vulnerabilities and Exposures CVE-2018-8540.Important

• All updates for Windows 8.1, Windows RT 8.1, and Windows Server 2012 R2 require that update KB 2919355 is installed. We recommend that you install update KB 2919355 on your Windows 8.1-based, Windows RT 8.1-based, or Windows Server 2012 R2-based computer so that you receive updates in the future.
• 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

The following articles contain additional information about this security update as it relates to individual product versions.

• [4470630](<https: //support.microsoft.com/help/4470630>) Description of the Security and Quality Rollup for .NET Framework 3.5 for Windows 8.1, RT 8.1, and Server 2012 R2 (KB 4470630)
• 4470622 Description of the Security and Quality Rollup for .NET Framework 4.5.2 for Windows 8.1, RT 8.1, and Server 2012 R2 (KB 4470622)
• 4470639 Description of the Security and Quality Rollup for .NET Framework 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, and 4.7.2 for Windows 8.1, RT 8.1, and Server 2012 R2 (KB 4470639)

How to obtain help and support for this security update

• Help for installing updates: Windows Update FAQ
• Protect yourself online and at home: Windows Security support
• Local support according to your country: International Support