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Vulnerabilities

Vulnerability · CVE-2026-96230

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

Published Oct 13, 2026 · catalog updated Oct 13, 2026 · Microsoft Security Advisory -

Check if you run it

No confirmed exploitation is on record for CVE-2026-96230. EPSS is 0.78%. Act only if a listed version of Microsoft Security Advisory - is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (Microsoft Security Advisory -).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High8.8
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.78%
Remediation
Version ranges on file
Affected products
nuget Microsoft.AspNetCore.Components.WebAssembly.Server

## 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

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • nuget Microsoft.AspNetCore.Components.WebAssembly.Server>= 10.0.0, <= 10.0.12
  • nuget Microsoft.AspNetCore.Components.WebAssembly.Server>= 11.0.0-preview.1, <= 11.0.0-rc.1
  • nuget Microsoft.AspNetCore.Components.WebAssembly.Server>= 8.0.0, <= 8.0.31
  • nuget Microsoft.AspNetCore.Components.WebAssembly.Server>= 9.0.0, <= 9.0.20

How to fix CVE-2026-96230

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-96230. EPSS is 0.78%. Act only if a listed version of Microsoft Security Advisory - is installed.

Which versions are affected?

Compare what you have installed with Microsoft.AspNetCore.Components.WebAssembly.Server >= 10.0.0, <= 10.0.12; Microsoft.AspNetCore.Components.WebAssembly.Server >= 11.0.0-preview.1, <= 11.0.0-rc.1; Microsoft.AspNetCore.Components.WebAssembly.Server >= 8.0.0, <= 8.0.31; Microsoft.AspNetCore.Components.WebAssembly.Server >= 9.0.0, <= 9.0.20. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-79: Cross-site Scripting (XSS). EPSS 0.78%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 13, 2026 · GitHub Advisory Database

    Detected

    ## 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-origi

  2. Oct 13, 2026 · GitHub Advisory Database

    Updated

    ## 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-origi

Sources

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.