Microsoft is releasing this security advisory to provide information 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 , propagate untrusted-input state through hyperlink , add TrueType font protection and XAML nesting-depth limits, and avoid caching positive DNS zone-policy decisions.
Announcement for this issue can be found at dotnet/announcements#451
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Weakness: CWE-502 (Deserialization of Untrusted Data)
The vulnerability affects Microsoft .NET projects that use an affected package version listed below.
How do I know if I am affected?
If using a package listed in affected packages , you're exposed to the vulnerability.
How do I fix the issue?
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.
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 dotnet --info command.
If you're using .NET 8.0, you should download and install .NET 8.0.32 Runtime or .NET 8.0.426 SDK from .
If you're using .NET 9.0, you should download and install .NET 9.0.21 Runtime or .NET 9.0.319 SDK from .
If you're using .NET 10.0, you should download and install .NET 10.0.13 Runtime or .NET 10.0.402 SDK from .
If you're using .NET 11.0, you should download and install .NET 11.0.0-rc.2 Runtime or .NET 11.0.100-rc.2 SDK from .
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 applications targeting any of the impacted versions, these applications are also vulnerable and must be recompiled and redeployed.
Reporting Security Issues
If you have 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 .
You can ask questions this issue on GitHub in the .NET GitHub organization. The main repos are located at . The Announcements repo ( ) will contain this bulletin as an issue and will include a link to a discussion issue. You can ask questions in the linked discussion issue.
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.
Vincent55 Yang ( )
V1.0 (10/13/2026): Advisory published.
The full story
This article is one source in a clustered incident — the cluster page carries the summary, timeline and every other outlet covering it.
