Findings

CVE-2026-96230

Microsoft Security Advisory CVE-2026-96230 - ASP.NET Core Remote Code Execution Vulnerability

Published Oct 13, 2026 · updated Oct 13, 2026

## Executive summary Microsoft is releasing this security advisory to provide information about a vulnerability 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 development-server debug page can reflect unencoded exception text, allowing cross-origin script injection through the unauthenticated endpoint used by . ## Announcement Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/478 ## CVSS Details - **Version:** 3.1 - **Severity:** High - **Score:** 8.8 - **Vector:** - **Weakness:** CWE-79 (Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')) ## Affected Platforms - **Platforms:** Windows, Linux, macOS - **Architectures:** All ## Affected Packages The vulnerability affects Microsoft .NET projects that use an affected package version listed below. Package name | Affected version | Patched version ------------ | ---------------- | --------------- [Microsoft.AspNetCore.Components.WebAssembly.Server](https://www.nuget.org/packages/Microsoft.AspNetCore.Components.WebAssembly.Server) | >= 10.0.0, = 11.0.0-preview.1, = 8.0.0, = 9.0.0, How do I know if I am affected? If using a package listed in [affected packages](#affected-packages), you're exposed to the vulnerability. ### How do I fix the issue? 1. To fix the issue please install the latest version of .NET. 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. 2. If your application references the vulnerable package, update the package reference to the patched version. You can list the versions you have installed by running the command. 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 applicatio