CVE-2023-36049

Microsoft Security Advisory CVE-2023-36049: .NET Elevation of Privilege Vulnerability

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

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

An elevation of privilege vulnerability exists in .NET where untrusted URIs provided to System.Net.WebRequest.Create can be used to inject arbitrary commands to backend FTP servers.

Announcement

Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/287

<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 6.0.24 or earlier.
• Any .NET 7.0 application running on .NET 7.0.13 or earlier.
• Any .NET 8.0 application running on .NET 8.0 RC2.

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 8.0 or .NET 7.0 or .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 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:   6.0.200
 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\6.0.300\

Host (useful for support):

  Version: 6.0.5
  Commit:  8473146e7d

.NET Core SDKs installed:

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

.NET Core runtimes installed:

  Microsoft.AspNetCore.App 6.0.5 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 6.0.5 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.WindowsDesktop.App 6.0.5 [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 should download and install Runtime 7.0.14 or SDK 7.0.114 (for Visual Studio 2022 v17.4) from https://dotnet.microsoft.com/download/dotnet-core/7.0.
• If you're using .NET 6.0, you should download and install Runtime 6.0.25 or SDK 6.0.317 (for Visual Studio 2022 v17.2) from https://dotnet.microsoft.com/download/dotnet-core/6.0.

.NET 6.0 and .NET 7.0 updates are also available from Microsoft Update. To access this either type "Check for updates" in your Windows search, or open Settings, choose Update & Security and then click Check for Updates.

Once you have installed the updated runtime or SDK, restart your apps for the update to take effect.

Additionally, if you've deployed self-contained applications targeting any of the impacted versions, these applications are also vulnerable and must be recompiled and redeployed.

Other Information

Reporting Security Issues

If you have found a potential security issue in .NET 8.0 or .NET 7.0 or .NET 6.0, please email details to [email protected].…

.NET, .NET Framework, and Visual Studio Elevation of Privilege 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.

.NET, .NET Framework, and Visual Studio Elevation of Privilege Vulnerability

.NET, .NET Framework, and Visual Studio Elevation of Privilege 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)