Withdrawn

This advisory was initially published and mapped incorrectly to nuget Microsoft.NETCore.App.Ref. We later reanalyzed this advisory and found it does not have a direct mapping to a NuGet package. Thus we have withdrawn this advisory.

The underlying ASP.NET Core Denial of Service Vulnerability and CVE-2021-31957 remain legitimate.

Description.

Microsoft is releasing this security advisory to provide information about a vulnerability in .NET 5.0 and .NET Core 3.1. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability.

A denial of service vulnerability exists when ASP.NET Core improperly handles client disconnect. An attacker who successfully exploited this vulnerability could cause a denial of service against an ASP.NET Core web application. The vulnerability can be exploited remotely, without authentication.

Patches

• If you’re using .NET 5.0, you should download and install Runtime 5.0.7 or SDK 5.0.204 (for Visual Studio 2019 v16.8) or SDK 5.0.301 (for Visual Studio 2019 16.10) from https://dotnet.microsoft.com/download/dotnet-core/5.0.

• If you’re using .NET Core 3.1, you should download and install Runtime 3.1.16 or SDK 3.1.116 (for Visual Studio 2019 v16.4) or 3.1.410 (for Visual Studio 2019 v16.5 or later) from https://dotnet.microsoft.com/download/dotnet-core/3.1.

Other Details

• Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/188
• An Issue for this can be found at https://github.com/dotnet/aspnetcore/issues/33369
• MSRC details for this can be found at https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2021-31957