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CVE-2026-83520

Microsoft Security Advisory CVE-2026-83520 - .NET and Visual Studio 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.WindowsDesktop.App.Runtime (WPF). This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability. Restrictive XAML and XPS security fixes block unsafe URI fetching and navigation, propagate untrusted-input state through hyperlink navigation, add TrueType font protection and XAML nesting-depth limits, and avoid caching positive DNS zone-policy decisions. ## Announcement Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/467 ## CVSS Details - **Version:** 3.1 - **Severity:** High - **Score:** 8.8 - **Vector:** - **Weakness:** CWE-502 (Deserialization of Untrusted Data) ## Affected Platforms - **Platforms:** Windows - **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.WindowsDesktop.App.Runtime.win-arm64](https://www.nuget.org/packages/Microsoft.WindowsDesktop.App.Runtime.win-arm64) | >= 11.0.0-preview.1, = 11.0.0-preview.1, = 11.0.0-preview.1, = 10.0.0, = 10.0.0, = 10.0.0, = 8.0.0, = 8.0.0, = 8.0.0, = 9.0.0, = 9.0.0, = 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 you

Code

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

Timeline

Detection, updates, and resolution for this record.

  1. Oct 13, 2026 · NCSC Netherlands

    Detected

    Microsoft heeft kwetsbaarheden verholpen in diverse componenten van de Developer Tools, zoals .NET en Visual Studio. Een kwaadwillende kan aanvallen uitvoeren die kunnen leiden tot de categoriën schade zoals weergegeven in de onderstaande tabellen. .NET: |------------------|------|-------------------------------------| | CVE-ID | CVSS | Impact | |------------------|------|-------------------------

  2. Oct 13, 2026 · GitHub Advisory Database

    Updated

    ## Executive summary Microsoft is releasing this security advisory to provide information about a vulnerability in Microsoft.WindowsDesktop.App.Runtime (WPF). This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability. Restrictive XAML and XPS security fixes block unsafe URI fetching and navigation, propagate untrusted-input state throu

Affected

  • nuget Microsoft.WindowsDesktop.App.Runtime.win-arm64>= 10.0.0, <= 10.0.12
  • nuget Microsoft.WindowsDesktop.App.Runtime.win-arm64>= 11.0.0-preview.1, <= 11.0.0-rc.1
  • nuget Microsoft.WindowsDesktop.App.Runtime.win-arm64>= 8.0.0, <= 8.0.31
  • nuget Microsoft.WindowsDesktop.App.Runtime.win-arm64>= 9.0.0, <= 9.0.20
  • nuget Microsoft.WindowsDesktop.App.Runtime.win-x64>= 10.0.0, <= 10.0.12
  • nuget Microsoft.WindowsDesktop.App.Runtime.win-x64>= 11.0.0-preview.1, <= 11.0.0-rc.1
  • nuget Microsoft.WindowsDesktop.App.Runtime.win-x64>= 8.0.0, <= 8.0.31
  • nuget Microsoft.WindowsDesktop.App.Runtime.win-x64>= 9.0.0, <= 9.0.20
  • nuget Microsoft.WindowsDesktop.App.Runtime.win-x86>= 10.0.0, <= 10.0.12
  • nuget Microsoft.WindowsDesktop.App.Runtime.win-x86>= 11.0.0-preview.1, <= 11.0.0-rc.1
  • nuget Microsoft.WindowsDesktop.App.Runtime.win-x86>= 8.0.0, <= 8.0.31
  • nuget Microsoft.WindowsDesktop.App.Runtime.win-x86>= 9.0.0, <= 9.0.20

Sources

  • CVE.orgVulnerability recordCVE-2026-83520

    Official CVE identifier

    cve.org
  • GitHub Advisory DatabasePackage advisoryGHSA-4w5f-7jp2-w48g

    Microsoft Security Advisory CVE-2026-83520 - .NET and Visual Studio Remote Code Execution Vulnerability

    github.com
  • NCSC NetherlandsGovernment advisoryCVE-2026-83520

    Microsoft heeft kwetsbaarheden verholpen in diverse componenten van de Developer Tools, zoals .NET en Visual Studio. Een kwaadwillende kan aanvallen uitvoeren die kunnen leiden tot de categoriën schade zoals weergegeven in de onderstaande tabellen. .NET: |------------------|-----

    advisories.ncsc.nl

References