Improper certificate validation in .NET Framework allows an unauthorized attacker to bypass a security feature over a network.

Affected: NuGet: Microsoft.NETCore.App.Runtime.linux-arm, NuGet: Microsoft.NETCore.App.Runtime.linux-arm64, NuGet: Microsoft.NETCore.App.Runtime.linux-musl-arm, NuGet: Microsoft.NETCore.App.Runtime.linux-musl-arm64, NuGet: Microsoft.NETCore.App.Runtime.linux-musl-x64, NuGet: Microsoft.NETCore.App.Runtime.linux-x64, NuGet: Microsoft.NETCore.App.Runtime.osx-arm64, NuGet: Microsoft.NETCore.App.Runtime.osx-x64

## Executive summary

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

.NET 11 post-handshake TLS client authentication can fail to verify the client certificate, allowing mutual-authentication requirements to be bypassed.

## Announcement

Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/464

## CVSS Details

- **Version:** 3.1 - **Severity:** Moderate - **Score:** 6.5 - **Vector:** `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N`

- **Weakness:** CWE-295 (Improper Certificate Validation) ## Affected Platforms

- **Platforms:** Linux, macOS - **Architectures:** All

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

The vulnerability affects Microsoft .NET projects that use an affected package version listed below.

Package name | Affected version | Patched version ------------ | ---------------- | --------------- [Microsoft.NETCore.App.Runtime.linux-arm](https://www.nuget.org/packages/Microsoft.NETCore.App.Runtime.linux-arm) | >= 11.0.0-preview.1, <= 11.0.0-rc.1 | 11.0.0-rc.2 [Microsoft.NETCore.App.Runtime.linux-arm64](https://www.nuget.org/packages/Microsoft.NETCore.App.Runtime.linux-arm64) | >= 11.0.0-preview.1, <= 11.0.0-rc.1 | 11.0.0-rc.2 [Microsoft.NETCore.App.Runtime.linux-musl-arm](https://www.nuget.org/packages/Microsoft.NETCore.App.Runt…