CVE-2023-36558

Microsoft Security Advisory CVE-2023-36558: .NET Security Feature Bypass Vulnerability

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

Microsoft is releasing this security advisory to provide information about a vulnerability in ASP.NET Core 6.0, ASP.NET Core 7.0 and, ASP.NET Core 8.0 RC2. This advisory also provides guidance on what developers can do to update their applications to address this vulnerability.

A security feature bypass vulnerability exists in ASP.NET where an unauthenticated user is able to bypass validation on Blazor server forms which could trigger unintended actions.

Announcement

Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/288

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

This vulnerability only affects ASP.NET Core Blazor apps. Other application types, including ASP.NET Core apps which do not utilize Blazor, are not affected.

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

• Any ASP.NET Core Blazor 6.0 application running on .NET 6.0.24 or earlier.
• Any ASP.NET Core Blazor 7.0 application running on .NET 7.0.13 or earlier.
• Any ASP.NET Core Blazor 8.0 application running on .NET 8.0 RC2.

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

<a name=".NET 7"></a>.NET 8.0

Package name | Affected version | Patched version ------------ | ---------------- | ------------------------- Microsoft.AspNetCore.Components | 8.0.0-rc.2.23480.2 | 8.0.0

<a name=".NET 7"></a>.NET 7.0

Package name | Affected version | Patched version ------------ | ---------------- | ------------------------- Microsoft.AspNetCore.Components | >= 7.0.0, < 7.0.13> | 7.0.14

<a name=".NET 7"></a>.NET 6.0

Package name | Affected version | Patched version ------------ | ---------------- | ------------------------- Microsoft.AspNetCore.Components | >= 6.0.0, < 6.0.24 | 6.0.25

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 or .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.
• 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:   7.0.200
 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\7.0.300\

Host (useful for support):

  Version: 76.0.5
  Commit:  8473146e7d

.NET Core SDKs installed:

  7.0.200 [C:\Program Files\dotnet\sdk]

.NET Core runtimes installed:

  Microsoft.AspNetCore.App 7.0.5 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 7.0.5 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.WindowsDesktop.App 7.0.5 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

To install additional .NET Core runtimes or SDKs:
  https://aka.ms/dotnet-download

• If you're using .NET 8.0, you should download and install .NET 8.0.0 Runtime or .NET 8.0.100 SDK (for Visual Studio 2022 v17.8) from https://dotnet.microsoft.com/download/dotnet-core/8.0.
• If you're using .NET 7.0, you…

ASP.NET Core Security Feature Bypass 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.

Security Fix(es):

• dotnet: Arbitrary File Write and Deletion Vulnerability: FormatFtpCommand (CVE-2023-36049)
• dotnet: ASP.NET Security Feature Bypass Vulnerability in Blazor forms (CVE-2023-36558)

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.

Security Fix(es):

• dotnet: Arbitrary File Write and Deletion Vulnerability: FormatFtpCommand (CVE-2023-36049)
• dotnet: ASP.NET Security Feature Bypass Vulnerability in Blazor forms (CVE-2023-36558)

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 7.0.114 and .NET Runtime 7.0.14.

Security Fix(es):

• dotnet: Arbitrary File Write and Deletion Vulnerability: FormatFtpCommand (CVE-2023-36049)
• dotnet: ASP.NET Security Feature Bypass Vulnerability in Blazor forms (CVE-2023-36558)

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 7.0.114 and .NET Runtime 7.0.14.

Security Fix(es):

• dotnet: Arbitrary File Write and Deletion Vulnerability: FormatFtpCommand (CVE-2023-36049)
• dotnet: ASP.NET Security Feature Bypass Vulnerability in Blazor forms (CVE-2023-36558)

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 6.0.125 and .NET Runtime 6.0.25.

Security Fix(es):

• dotnet: Arbitrary File Write and Deletion Vulnerability: FormatFtpCommand (CVE-2023-36049)
• dotnet: ASP.NET Security Feature Bypass Vulnerability in Blazor forms (CVE-2023-36558)

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 6.0.125 and .NET Runtime 6.0.25.

Security Fix(es):

• dotnet: Arbitrary File Write and Deletion Vulnerability: FormatFtpCommand (CVE-2023-36049)
• dotnet: ASP.NET Security Feature Bypass Vulnerability in Blazor forms (CVE-2023-36558)

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.

ASP.NET Core Security Feature Bypass Vulnerability

ASP.NET Core Security Feature Bypass Vulnerability

ASP.NET Core Security Feature Bypass 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 7.0.114 and .NET Runtime 7.0.14.

Security Fix(es):

• dotnet: Arbitrary File Write and Deletion Vulnerability: FormatFtpCommand (CVE-2023-36049)

• dotnet: ASP.NET Security Feature Bypass Vulnerability in Blazor forms (CVE-2023-36558)

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 6.0.125 and .NET Runtime 6.0.25.

Security Fix(es):

• dotnet: Arbitrary File Write and Deletion Vulnerability: FormatFtpCommand (CVE-2023-36049)

• dotnet: ASP.NET Security Feature Bypass Vulnerability in Blazor forms (CVE-2023-36558)

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.

Barry Dorrans discovered that .NET did not properly implement certain security features for Blazor server forms. An attacker could possibly use this issue to bypass validation, which could trigger unintended actions. (CVE-2023-36558)

Piotr Bazydlo discovered that .NET did not properly handle untrusted URIs provided to System.Net.WebRequest.Create. An attacker could possibly use this issue to inject arbitrary commands to backend FTP servers. (CVE-2023-36049)