May 12, 2020-KB4552927 Cumulative Update for .NET Framework 4.8 for Windows 10 Version 1703

Applies to: .NET Framework

Summary


A remote code execution vulnerability exists in .NET Framework software when the software fails to check the source markup of a file. An attacker who successfully exploited the vulnerability could run arbitrary code in the context of the current user. If the current user is logged on with administrative user rights, an attacker could take control of the affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights. Exploitation of the vulnerability requires that a user open a specially crafted file with an affected version of .NET Framework. In an email attack scenario, an attacker could exploit the vulnerability by sending the specially crafted file to the user and convincing the user to open the file. The security update addresses the vulnerability by correcting how .NET Framework checks the source markup of a file.

To learn more about the vulnerabilities, go to the following Common Vulnerabilities and Exposures (CVE).

A denial of service vulnerability exists when .NET Framework improperly handles web requests. An attacker who successfully exploited this vulnerability could cause a denial of service against a .NET Framework web application. The vulnerability can be exploited remotely, without authentication. A remote unauthenticated attacker could exploit this vulnerability by issuing specially crafted requests to the .NET Framework application. The update addresses the vulnerability by correcting how the .NET Framework web application handles web requests.

To learn more about the vulnerabilities, go to the following Common Vulnerabilities and Exposures (CVE).

Quality and reliability improvements

Winforms

- Addresses an issue with WinForms ComboBox control reinitialization in AD FS MMC UI.

- Adresses an issue getting accessible objects for PropertyGridView ComboBox property items - adding the verification for item existence and validity.

- Addresses an issue with interaction between WPF user control and hosting WinForms app when processing keyboard input.

Workflow

- Addresses an accessibility issue where text inside a Windows Workflow Foundation Visual Basic Editor would use the wrong colors in high contrast themes.

CLR1

- Addresses rare crashes that could occur if Server GC is enabled and a GC occurs while another thread is running NGen'ed code which is making the initial call into NGen'ed code in a 2nd module where one or more parameter types involve valuetypes defined in a 3rd module.

- Addresses crashes that could occur in certain scenarios involving hot-added CPUs and/or multi-group machines where per-group CPU count is not consistent across all groups

- Addresses rare crashes or deadlocks that could occur if a GC occurs while another thread is running NGen'ed code which is making the initial call into a static method within the same module where one or more parameter types involve type-forwarded valuetypes.

- Addresses rare crashes that could occur during the first call that native code makes into the managed portion of a mixed-mode DLL.


1 Common Language Runtime (CLR)

Known issues in this update


Microsoft is not currently aware of any issues in this update.

How to get this update


Install this update

This update will be downloaded and installed automatically from Windows Update.

To get the standalone package for this update, go to the Microsoft Update Catalog website.

File information

For a list of the files that are provided in this update, download the file information for cumulative update .

Information about protection and security