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 exploits 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 by using administrative user rights.
To exploit the vulnerability, an attacker must first convince the user to open a malicious document or application.This security update addresses the vulnerability by correcting how the .NET Framework validates untrusted input. To learn more about this vulnerability, see Microsoft Common Vulnerabilities and Exposures CVE-2017-8759.
- All updates for Windows RT 8.1, Windows 8.1, and Windows Server 2012 R2 require update 2919355 to be installed. We recommend that you install update 2919355 on your Windows RT 8.1-based, Windows 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.
Update replacement information
Additional information about this security update
- 4040956 Description of the Security Only update for the .NET Framework 4.6, 4.6.1, 4.6.2, and 4.7 for Windows 8.1, Windows RT 8.1 and Windows Server 2012 R2: September 12, 2017
- 4040958 Description of the Security Only update for the .NET Framework 4.5.2 for Windows 8.1, Windows RT 8.1, and Windows Server 2012 R2: September 12, 2017
- 4040967 Description of the Security Only update for the .NET Framework 3.5 for Windows 8.1, Windows RT 8.1, and Windows Server 2012 R2: September 12, 2017
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
- Microsoft .NET Framework 3.5, 4.5.2, 4.6, 4.6.1, 4.6.2, and 4.7 when used with:
- Windows Server 2012 R2
- Windows RT 8.1
- Windows 8.1