Release Date:May 12, 2020
Version: .NET Framework 3.5 and 4.8
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).
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.
Additional information about this update
The following articles contain additional information about this update as it relates to individual product versions.
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4556441 Description of the Cumulative Update for .NET Framework 3.5, 4.7.2 and 4.8 for Windows 10 Version 1809 and Windows Server 2019 (KB4556441)
Information about protection and security
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Protect yourself online: Windows Security support
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Learn how we guard against cyber threats: Microsoft Security
