CVE-2023-21538

Microsoft Security Advisory CVE-2023-21538: .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 6.0. 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 6.0 where a malicious client could cause a stack overflow which may result in a denial of service attack when an attacker sends an invalid request to an exposed endpoint.

Discussion

Discussion for this issue can be found at https://github.com/dotnet/runtime/issues/80449

<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 6.0 application running on .NET 6.0.12 or earlier.

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

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

Package name | Affected version | Patched version ------------ | ---------------- | ------------------------- Microsoft.NetCore.App.Runtime.linux-arm|>= 6.0.0, <= 6.0.12|6.0.13 Microsoft.NetCore.App.Runtime.linux-arm64|>= 6.0.0, <= 6.0.12|6.0.13 Microsoft.NetCore.App.Runtime.linux-musl-arm|>= 6.0.0, <= 6.0.12|6.0.13 Microsoft.NetCore.App.Runtime.linux-musl-arm64|>= 6.0.0, <= 6.0.12|6.0.13 Microsoft.NetCore.App.Runtime.linux-musl-x64|>= 6.0.0, <= 6.0.12|6.0.13 Microsoft.NetCore.App.Runtime.linux-x64|>= 6.0.0, <= 6.0.12|6.0.13 Microsoft.NetCore.App.Runtime.osx-arm64|>= 6.0.0, <= 6.0.12|6.0.13 Microsoft.NetCore.App.Runtime.osx-x64|>= 6.0.0, <= 6.0.12|6.0.13 Microsoft.NetCore.App.Runtime.win-arm|>= 6.0.0, <= 6.0.12|6.0.13 Microsoft.NetCore.App.Runtime.win-arm64|>= 6.0.0, <= 6.0.12|6.0.13 Microsoft.NetCore.App.Runtime.win-x64|>= 6.0.0, <= 6.0.12|6.0.13 Microsoft.NetCore.App.Runtime.win-x86|>= 6.0.0, <= 6.0.12|6.0.13

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 6.0. 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.
• If you have .NET Core 3.1 or greater installed, you can list the versions you have installed by running the dotnet --info command. You will see output like the following;
• If you are using one of the affected packages, please update to the patched version listed above.

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

 Version:   6.0.300
 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):

 …

.NET is a managed-software framework. It implements a subset of the .NET framework APIs and several new APIs, and it includes a CLR implementation.

New versions of .NET that address a security vulnerability are now available. The updated versions are .NET SDK 6.0.113 and .NET Runtime 6.0.13.

The following packages have been upgraded to a later upstream version: dotnet6.0 (6.0.113). (BZ#2154459)

Security Fix(es):

• dotnet: Parsing an empty HTTP response as a JSON.NET JObject causes a stack overflow and crashes a process (CVE-2023-21538)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

.NET is a managed-software framework. It implements a subset of the .NET framework APIs and several new APIs, and it includes a CLR implementation.

New versions of .NET that address a security vulnerability are now available. The updated versions are .NET SDK 6.0.113 and .NET Runtime 6.0.13.

The following packages have been upgraded to a later upstream version: dotnet6.0 (6.0.113). (BZ#2154458)

Security Fix(es):

• dotnet: Parsing an empty HTTP response as a JSON.NET JObject causes a stack overflow and crashes a process (CVE-2023-21538)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

.NET Denial of Service Vulnerability

.NET is a managed-software framework. It implements a subset of the .NET framework APIs and several new APIs, and it includes a CLR implementation.

New versions of .NET that address a security vulnerability are now available. The updated versions are .NET SDK 6.0.113 and .NET Runtime 6.0.13.

The following packages have been upgraded to a later upstream version: dotnet6.0 (6.0.113). (BZ#2154459)

Security Fix(es):

• dotnet: Parsing an empty HTTP response as a JSON.NET JObject causes a stack overflow and crashes a process (CVE-2023-21538)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

.NET is a managed-software framework. It implements a subset of the .NET framework APIs and several new APIs, and it includes a CLR implementation.

New versions of .NET that address a security vulnerability are now available. The updated versions are .NET SDK 6.0.113 and .NET Runtime 6.0.13.

The following packages have been upgraded to a later upstream version: dotnet6.0 (6.0.113). (BZ#2154458)

Security Fix(es):

• dotnet: Parsing an empty HTTP response as a JSON.NET JObject causes a stack overflow and crashes a process (CVE-2023-21538)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

.NET Denial of Service Vulnerability

.NET Denial of Service Vulnerability

.NET Denial of Service Vulnerability

Johan Gorter discovered that .NET 6 incorrectly processed certain invalid HTTP requests. An attacker could possibly use this issue to cause a denial of service condition for an exposed endpoint.