Microsoft Security Advisory CVE-2026-50651 – .NET Denial of Service Vulnerability

Executive summary

Microsoft is releasing this security advisory to provide information about a vulnerability in .NET HTTP client (System.Net.Http). This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability.

A denial of service vulnerability exists in .NET 8, .NET 9, and .NET 10 where an attacker can exploit the HTTP/2 protocol to cause an out-of-memory condition.

Announcement

Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/422

CVSS Details

• Version: 3.1
• Severity: High
• Score: 7.5
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
• Weakness: CWE-770 (Allocation of Resources Without Limits or Throttling)

Affected Platforms

• Platforms: All
• Architectures: All

<a name="affected-packages"></a>Affected Packages

The vulnerability affects any Microsoft .NET project if it uses any of affected package versions listed below

<a name=".NET 10.0"></a>.NET 10.0

<a name=".NET 9.0"></a>.NET 9.0

<a name=".NET 8.0"></a>.NET 8.0

Advisory FAQ

<a name="how-affected"></a>How do I know if I am affected?

If using a package listed in affected packages, you're exposed to the vulnerability.

<a name="how-fix"></a>How do I fix the issue?

1. To fix the issue please install the latest version of .NET. If you have installed one or more .NET SDKs through Visual Studio, Visual Studio will prompt you to update Visual Studio, which will also update your .NET SDKs.
2. If your application references the vulnerable nuget package, update the package reference to the patched version. You can list the versions you have installed by running the dotnet --info command.

Once you have installed the updated runtime or SDK, restart your apps for the u