Improper control of generation of code ('code injection') in ASP.NET Core allows an unauthorized attacker to execute code over a network.

Affected: NuGet: Microsoft.AspNetCore.Components.WebAssembly.Server

## Executive summary

Microsoft is releasing this security advisory to provide information about a vulnerability in the Blazor WebAssembly debugger included in `Microsoft.AspNetCore.Components.WebAssembly.Server`. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability.

The Blazor WebAssembly debug proxy evaluates debugger expressions by generating and compiling C# source. Certain values originating in the application being debugged, including `ToString()` results, descriptions, and class names, are embedded in that generated source without consistent escaping. An attacker-controlled value can escape the generated string literal and execute code on a developer's machine when the developer evaluates an expression during debugging.

## Announcement

Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/445

## CVSS Details

- **Version:** 3.1 - **Severity:** High - **Score:** 8.8 - **Vector:** `CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H` - **Weakness:** CWE-94 (Improper Control of Generation of Code ('Code Injection'))

## Affected Platforms

- **Platforms:** Windows, 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.AspNe…