GHSA-gh2h-rhph-h37g Microsoft Security Advisory CVE-2026-50646 – .NET Remote Code Execution Vulnerability

• NuGet Microsoft.WindowsDesktop.App.Runtime.win-x64: >= 10.0.0, < 10.0.10 → fixed in 10.0.10 • NuGet Microsoft.WindowsDesktop.App.Runtime.win-x86: >= 10.0.0, < 10.0.10 → fixed in 10.0.10 • NuGet Microsoft.WindowsDesktop.App.Runtime.win-arm64: >= 10.0.0, < 10.0.10 → fixed in 10.0.10 • NuGet Microsoft.WindowsDesktop.App.Runtime.win-x64: >= 9.0.0, < 9.0.18 → fixed in 9.0.18 • NuGet Microsoft.WindowsDesktop.App.Runtime.win-x86: >= 9.0.0, < 9.0.18 → fixed in 9.0.18 • NuGet Microsoft.WindowsDesktop.App.Runtime.win-arm64: >= 9.0.0, < 9.0.18 → fixed in 9.0.18 • NuGet Microsoft.WindowsDesktop.App.Runtime.win-x64: >= 8.0.0, < 8.0.29 → fixed in 8.0.29 • NuGet Microsoft.WindowsDesktop.App.Runtime.win-x86: >= 8.0.0, < 8.0.29 → fixed in 8.0.29 • NuGet Microsoft.WindowsDesktop.App.Runtime.win-arm64: >= 8.0.0, < 8.0.29 → fixed in 8.0.29

Executive summary Microsoft is releasing this security advisory to provide information about a vulnerability in Windows Presentation Foundation (WPF). This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability. A remote code execution vulnerability exists in Windows Presentation Foundation (WPF) in .NET 8, .NET 9, and .NET 10 when parsing specially crafted XAML input. An attacker who successfully exploits this vulnerability could execute arbitrary code in the context of the current user. Announcement Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/TBD CVSS Details • Version: 3.1 • Severity: High • Score: 7.8 • Vector: `CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H` • Weakness: CWE-693 (Protection Mechanism Failure) Affected Platforms • Platforms: Windows • Architectures: All Affected Packages The vulnerability affects any Microsoft .NET project if it uses any of affected package versions listed below .NET 10.0 Package name | Affected version | Patched version ------------ | ---------------- | ------------------------- Microsoft.WindowsDesktop.App.Runtime.win-arm64 | >= 10.0.0, = 10.0.0, = 10.0.0, .NET 9.0 Package name | Affected version | Patched version ------------ | ---------------- | ------------------------- Microsoft.WindowsDesktop.App.Runtime.win-arm64 | >= 9.0.0, = 9.0.0, = 9.0.0, .NET 8.0 Package name | Affected version | Patched version ------------ | ---------------- | ------------------------- Microsoft.WindowsDesktop.App.Runtime.win-arm64 | >= 8.0.0, = 8.0.0, = 8.0.0, How do I know if I am affected? If using a package listed in affected packages, developers exposed to the vulnerability. How do I fix the issue? 1. To fix the issue please install the latest version of .NET. If developers have installed one or more .NET SDKs through Visual Studio, Visual Studio will prompt them to update Visual Studio, which will also update their .NET SDKs. 2. If their application references the vulnerable nuget package, update the package reference to the patched version. Developers can list the versions they have installed by running the `dotnet --info` command. Once developers have installed the updated runtime or SDK, they should restart their apps for the update to take effect. Additionally, if they've deployed self-contained applications targeting any of the impacted versions, these applications are also vulnerable and must be recompiled and redeployed. Other Information Reporting Security Issues If anyone has found a potential security issue in a supported version of .NET, please report it to the Microsoft Security Response Center (MSRC) via the MSRC Researcher Portal. Further information can be found in the MSRC Report an Issue FAQ. Security reports made through MSRC may qualify for the Microsoft .NET Bounty. Details of the Microsoft .NET Bounty Program including terms and conditions are at https://aka.ms/corebounty. Support Direct questions about this issue to GitHub in the .NET GitHub organization. The main repos are located at https://github.com/dotnet/runtime. The Announcements repo (https://github.com/dotnet/Announcements) will contain this bulletin as an issue and will include a link to a discussion issue. Users can ask questions in the linked discussion issue. Disclaimer The information provided in this advisory is provided "as is" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply. External Links CVE-2026-50646 Acknowledgements Kevin Gosse, 41ae55e9310ff27fa6f26af4727e5590, Ky0toFu Revisions V1.0 (July 14, 2026): Advisory published.