This update resolves a vulnerability in Microsoft .NET Framework that could allow a Denial of Service attack when .NET Framework and .NET core components process XML documents incorrectly. An attacker who successfully exploits this vulnerability could cause a denial of service against a .NET Framework application. To learn more about this vulnerability, see Microsoft Common Vulnerabilities and Exposures CVE-2018-0765.
Additionally, this update resolves a security feature bypass vulnerability in Windows that could allow an attacker to bypass Device Guard. An attacker who successfully exploits this vulnerability could circumvent a User Mode Code Integrity (UMCI) policy on the computer. To learn more about this vulnerability, see Microsoft Common Vulnerabilities and Exposures CVE-2018-1039.
- 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.
Quality and reliability improvements
1 Common Language Runtime (CLR)
Additional information about this security update
For more information about this security update as it relates to Windows 8.1, Windows RT 8.1 and Windows Server 2012 R2, see the following article in the Microsoft Knowledge Base:
4099639 Security Only update for .NET Framework 3.5 SP1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, and 4.7.1 updates for Windows 8.1, RT 8.1 and Server 2012 R2 (KB 4099639)
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.
Method 2: 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 opens a browser window in which you may be prompted to install an ActiveX control. You must install the ActiveX control to continue.
- After the control is installed, you see the Microsoft Update Catalog screen. Enter 4099639 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.
- After you select all the packages that you need, click View Basket.
- To import the packages to your WSUS server, click Import.
- After the packages are imported, click 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:
20180508 Security update deployment information: May 8, 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.
The English (United States) version of this software update installs files that have the attributes that are listed in the following tables. The dates and the times for these files are listed in Coordinated Universal Time (UTC). The dates and the 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 the times may change when you perform certain operations on the files.
Windows 8.1, Windows RT 8.1 and Windows Server 2012 R2 file information
The MANIFEST files (.manifest) and MUM files (.mum) that are installed are not listed.
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