Summary
This security update resolves the following vulnerabilities:
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A "remote code execution" vulnerability exists when .NET Framework does not validate input correctly. An attacker who successfully exploits this vulnerability 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 have administrative user rights. To exploit the vulnerability, an attacker would have to pass specific input to an application through 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-2018-8284.
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An "elevation of privilege" vulnerability exists in .NET Framework that could allow an attacker to elevate their user rights level. To exploit the vulnerability, an attacker would first have to access the local computer, and then run a malicious program. This update addresses the vulnerability by correcting how .NET Framework enables COM objects. To learn more about this vulnerability, see Microsoft Common Vulnerabilities and Exposures CVE-2018-8202.
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A "security feature bypass" vulnerability exists when .NET Framework components do not correctly validate certificates. An attacker could present expired certificates when challenged. This security update addresses the vulnerability by making sure that .NET Framework components correctly validate certificates. To learn more about this vulnerability, see Microsoft Common Vulnerabilities and Exposures CVE-2018-8356.
Important
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All updates for .NET Framework 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, and 4.7.2 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.
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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.
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4338612 Description of the Security Only update for .NET Framework 3.5.1 for Windows 7 SP1 and Server 2008 R2 SP1 (KB 4338612)
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4338602 Description of the Security Only update for .NET Framework 4.5.2 for Windows 7 SP1, Server 2008 R2 SP1, and Server 2008 (KB 4338602)
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4338606 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 (KB 4338606)
Known issues
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After you install any of the July 2018 .NET Framework Security Updates, a COM component fails to load because of “access denied,” “class not registered,” or “internal failure occurred for unknown reasons” errors. The most common failure signature is the following:
Exception type: System.UnauthorizedAccessException
Message: Access is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED))
For more information about this issue, see the following article in the Microsoft Knowledge Base:
4345913 "Access Denied" errors and applications with COM activation fail after installing July 2018 Security and Quality Rollup updates for .NET Framework
To resolve this issue, install the August Security Only update KB 4345679.
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Assume that you run the Azure Active Directory (Azure AD) Connect Health for Sync monitoring agent on a system that has .NET Framework 4.7.2 or the July 2018 updates for .NET Framework 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, or 4.7.2 installed. In this scenario, the system may experience slow performance and high CPU usage. For more information about this issue, see the following article in the Microsoft Knowledge Base:
4457331 Slow performance and high CPU usage in Azure AD Connect Health for Sync monitoring agent on a system that has installed .NET Framework 4.7.2 or the July 2018 updates for .NET Framework 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, or 4.7.2
How to obtain help and support for this security update
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Help for installing updates: Windows Update FAQ
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Security solutions for IT professionals: TechNet Security Support and Troubleshooting
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Help for protecting your Windows-based products and services from viruses and malware: Microsoft Secure
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Local support according to your country: International Support
