CVE-2026-85363: Microsoft .NET Windows Desktop App Runtime integer overflow in glyph processing

CVE-2026-85363 · Severity: high · CVSS 8.8 · Published 2026-10-13

Microsoft .NET Windows Desktop App Runtime is used to run Windows desktop applications built with .NET. An attacker can craft a malicious XPS file that, when opened by a user, exploits an integer overflow vulnerability in glyph coordinate handling, leading to out-of-bounds memory writes. This can result in remote code execution or application crash.

Technologies: Microsoft.WindowsDesktop.App.Runtime.win-arm64 (NuGet), Microsoft.WindowsDesktop.App.Runtime.win-x64 (NuGet), Microsoft.WindowsDesktop.App.Runtime.win-x86 (NuGet). Vendors: Microsoft, NuGet.

Quick answers

Is CVE-2026-85363 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-85363 being exploited in the wild.
How severe is CVE-2026-85363?
High severity, with a CVSS score of 8.8, published 13 October 2026.
Which products and versions are affected?
Microsoft .NET Windows Desktop App Runtime 8.0.0 through 8.0.31, 9.0.0 through 9.0.20, 10.0.0 through 10.0.12, 11.0.0-preview.1 through 11.0.0-rc.1; Microsoft.WindowsDesktop.App.Runtime.win-arm64 (NuGet) >= 8.0.0, <= 8.0.31, ECOSYSTEM:introduced=8.0.0,fixed=8.0.32; Microsoft.WindowsDesktop.App.Runtime.win-x64 (NuGet) >= 8.0.0, <= 8.0.31, ECOSYSTEM:introduced=8.0.0,fixed=8.0.32; Microsoft.WindowsDesktop.App.Runtime.win-x86 (NuGet) >= 8.0.0, <= 8.0.31, ECOSYSTEM:introduced=8.0.0,fixed=8.0.32.
Is there a fix for CVE-2026-85363?
Yes. Microsoft.WindowsDesktop.App.Runtime.win-arm64 (NuGet): upgrade to 8.0.32 or later; Microsoft.WindowsDesktop.App.Runtime.win-x64 (NuGet): upgrade to 8.0.32 or later; Microsoft.WindowsDesktop.App.Runtime.win-x86 (NuGet): upgrade to 8.0.32 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-85363 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-85363?
Check whether you run Microsoft .NET Windows Desktop App Runtime, Microsoft.WindowsDesktop.App.Runtime.win-arm64 (NuGet), Microsoft.WindowsDesktop.App.Runtime.win-x64 (NuGet) or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • Microsoft.WindowsDesktop.App.Runtime.win-arm64 (NuGet): upgrade to 8.0.32 or later
    dotnet add package Microsoft.WindowsDesktop.App.Runtime.win-arm64 --version 8.0.32
  • Microsoft.WindowsDesktop.App.Runtime.win-x64 (NuGet): upgrade to 8.0.32 or later
    dotnet add package Microsoft.WindowsDesktop.App.Runtime.win-x64 --version 8.0.32
  • Microsoft.WindowsDesktop.App.Runtime.win-x86 (NuGet): upgrade to 8.0.32 or later
    dotnet add package Microsoft.WindowsDesktop.App.Runtime.win-x86 --version 8.0.32

Technical details

An integer overflow vulnerability exists in the CD3DGlyphBank::RectFillAlpha function when processing attacker-controlled XPS glyph coordinates. The overflow causes destination pointer arithmetic to overflow, resulting in out-of-bounds write. The vulnerability requires user interaction (opening a malicious XPS file) and can be exploited over the network.

Affected products

  • Microsoft .NET Windows Desktop App Runtime 8.0.0 through 8.0.31, 9.0.0 through 9.0.20, 10.0.0 through 10.0.12, 11.0.0-preview.1 through 11.0.0-rc.1

Identifiers

  • CVE-2026-85363
  • GHSA-f63g-mx39-3r38

Timeline

  • 2026-10-13: advisory

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