CVE-2023-38178

Microsoft Security Advisory CVE-2023-38178: .NET Denial of Service Vulnerability

<a name="executive-summary"></a>Executive summary

Microsoft is releasing this security advisory to provide information about a vulnerability in .NET 7.0. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability.

A vulnerability exists in .NET Kestrel where a malicious client can bypass QUIC stream limit in HTTP/3 in both ASP.NET and .NET runtimes resulting in denial of service.

Announcement

Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/268

<a name="mitigation-factors"></a>Mitigation factors

Microsoft has not identified any mitigating factors for this vulnerability.

<a name="affected-software"></a>Affected software

• Any .NET 7.0 application running on .NET 7.0.9 or earlier.

If your application uses the following package versions, ensure you update to the latest version of .NET.

<a name=".NET 7"></a>.NET 7

Package name | Affected version | Patched version ------------ | ---------------- | ------------------------- Microsoft.AspNetCore.App.Runtime.win-arm64 | >= 7.0.0, <= 7.0.9 | 7.0.10 Microsoft.AspNetCore.App.Runtime.win-arm | >= 7.0.0, <= 7.0.9 | 7.0.10 Microsoft.AspNetCore.App.Runtime.win-x64 | >= 7.0.0, <= 7.0.9 | 7.0.10 Microsoft.AspNetCore.App.Runtime.win-x86 | >= 7.0.0, <= 7.0.9 | 7.0.10 [Microsoft.NetCore.App.Runtime.win-arm](https://www.nuget.org/packages/ Microsoft.NetCore.App.Runtime.win-arm) | >= 7.0.0, <= 7.0.9 | 7.0.10 Microsoft.NetCore.App.Runtime.win-arm | >= 7.0.0, <= 7.0.9 | 7.0.10 Microsoft.NetCore.App.Runtime.win-x86 | >= 7.0.0, <= 7.0.9 | 7.0.10 Microsoft.NetCore.App.Runtime.win-x64 | >= 7.0.0, <= 7.0.9 | 7.0.10

<a name=".NET 6"></a>.NET 6

.NET 6 included HTTP/3 support as a preview feature , which requires specific opt-in code. If you are using HTTP/3 in .NET 6 you must update your application to .NET 7, where the feature is supported, to fix the vulnerability. Future versions of .NET will disable the preview feature entirely.

Advisory FAQ

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

If you have a runtime or SDK with a version listed, or an affected package listed in affected software, you're exposed to the vulnerability.

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

• To fix the issue please install the latest version of .NET 7.0. 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.
• To fix this issue on Linux, please update libmsquic to 2.2+
• If you are using one of the affected packages, please update to the patched version listed above.
• If you have .NET 6.0 or greater installed, you can list the versions you have installed by running the dotnet --info command. You will see output like the following;

.NET Core SDK (reflecting any global.json):

 Version:   7.0.400
 Commit:    8473146e7d

Runtime Environment:

 OS Name:     Windows
 OS Version:  10.0.18363
 OS Platform: Windows
 RID:         win10-x64
 Base Path:   C:\Program Files\dotnet\sdk\6.0.300\

Host (useful for support):

  Version: 7.0.10
  Commit:  8473146e7d

.NET Core SDKs installed:
…

.NET Core and Visual Studio Denial of Service Vulnerability

.NET Core and Visual Studio Denial of Service Vulnerability

.NET Core and Visual Studio Denial of Service Vulnerability

USN-6278-1 fixed several vulnerabilities in .NET. This update provides the corresponding updates for Ubuntu 22.04 LTS.

Original advisory details:

It was discovered that .NET did properly handle the execution of certain commands. An attacker could possibly use this issue to achieve remote code execution. (CVE-2023-35390)

Benoit Foucher discovered that .NET did not properly implement the QUIC stream limit in HTTP/3. An attacker could possibly use this issue to cause a denial of service. (CVE-2023-38178)

It was discovered that .NET did not properly handle the disconnection of potentially malicious clients interfacing with a Kestrel server. An attacker could possibly use this issue to cause a denial of service. (CVE-2023-38180)