ASP.NET Core Denial of Service Vulnerability
Exact source revision recorded 23 Oct 2026 16:01:25 UTC. It does not establish the source's current position. Latest evidence.
osv · GHSA-mcwm-2wmc-6hv4
Withdrawn# Withdrawn This advisory was initially published and mapped incorrectly to nuget `Microsoft.NETCore.App.Ref`.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 Thus we have withdrawn this advisory.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
- Source published
- 6 Oct 2021 00:23:01 UTC
- Source modified
- 10 Sep 2026 03:49:16 UTC
- Observed here
- 23 Oct 2026 16:01:25 UTC
- Source terms
- GitHub Advisory Database · CC-BY-4.0
Original source record · Cite this exact observation · Complete original publisher JSON
This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.
CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Publisher rating · HIGH