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

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

8.8 · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

EPSS

• CVE-2026-96230: 0.95% estimated exploitation activity in the next 30 days; percentile 61.16 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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 /framework/debug endpoint used by dotnet watch. 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: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H - Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')) Affected Platforms - Platforms: Windows, Linux, macOS - Architectures: All <a name="affected-packages"</aAffected Packages The vulnerability affects Microsoft .NET projects that…

Published by the source

13 Oct 2026, 20:51 UTC

Last modified by the source

19 Oct 2026, 19:30 UTC

Source last checked

26 Oct 2026, 17:05 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-qjpx-jqm5-h2c4

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-qjpx-jqm5-h2c4

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# Patch Next advisory brief: CVE-2026-96230

Advisory: Microsoft Security Advisory CVE-2026-96230 - ASP.NET Core Remote Code Execution Vulnerability
IDs: CVE-2026-96230, GHSA-qjpx-jqm5-h2c4
Record: https://patchnext.com/advisories/cve-2026-96230 (revision 2, source checked 26 Oct 2026, 17:05 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: microsoft.aspnetcore.components.webassembly.server 11.0.0-rc.2, 10.0.13, 9.0.21, 8.0.32. A vendor fix does not mean a deployment is fixed.

## Affected components
- NuGet microsoft.aspnetcore.components.webassembly.server: affected >= 10.0.0, <= 10.0.12; >= 11.0.0-preview.1, <= 11.0.0-rc.1; >= 8.0.0, <= 8.0.31; >= 9.0.0, <= 9.0.20; fixed in 11.0.0-rc.2, 10.0.13, 8.0.32, 9.0.21

## Suggested inspection (read-only)
- NuGet microsoft.aspnetcore.components.webassembly.server: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on microsoft.aspnetcore.components.webassembly.server.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-qjpx-jqm5-h2c4 (OSV record GHSA-qjpx-jqm5-h2c4 lists affected ranges: NuGet microsoft.aspnetcore.components.webassembly.server >=10.0.0 =11.0.0-preview.1 =8.0.0 =9.0.0 <9.0.21 (fixed))
- Verified: https://github.com/advisories/GHSA-qjpx-jqm5-h2c4 (GitHub-reviewed advisory GHSA-qjpx-jqm5-h2c4 lists affected ranges: NuGet microsoft.aspnetcore.components.webassembly.server >=10.0.0 =11.0.0-preview.1 =8.0.0 =9.0.0 <=9.0.20)

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