CVE-2026-62871

Out-of-bounds write in .NET allows an unauthorized attacker to execute code locally.

Out-of-bounds write in .NET allows an unauthorized attacker to execute code locally.

Executive summary

Microsoft is releasing this security advisory to provide information about a vulnerability in Windows Presentation Foundation. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability.

Out-of-bounds write in .NET allows an unauthorized attacker to execute code locally.

Announcement

Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/431

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/E:U/RL:O/RC:C
• Weakness: CWE-787: Out-of-bounds Write; CWE-122: Heap-based Buffer Overflow

Affected Platforms

• Platforms: Windows
• Architectures: All

<a name="affected-packages"></a>Affected Packages

The vulnerability affects any Microsoft .NET project if it uses any of affected package versions listed below

<a name=".NET 10"></a>.NET 10

Package name | Affected version | Patched version ------------ | ---------------- | ------------------------- Microsoft.WindowsDesktop.App.Runtime.win-arm64 | >= 10.0.0, <= 10.0.10 | 10.0.11 Microsoft.WindowsDesktop.App.Runtime.win-x64 | >= 10.0.0, <= 10.0.10 | 10.0.11 Microsoft.WindowsDesktop.App.Runtime.win-x86 | >= 10.0.0, <= 10.0.10 | 10.0.11

<a name=".NET 9"></a>.NET 9

Package name | Affected version | Patched version ------------ | ---------------- | ------------------------- Microsoft.WindowsDesktop.App.Runtime.win-arm64 | >= 9.0.0, <= 9.0.18 | 9.0.19 Microsoft.WindowsDesktop.App.Runtime.win-x64 | >= 9.0.0, <= 9.0.18 | 9.0.19 Microsoft.WindowsDesktop.App.Runtime.win-x86 | >= 9.0.0, <= 9.0.18 | 9.0.19

<a name=".NET 8"></a>.NET 8

Package name | Affected version | Patched version ------------ | ---------------- | ------------------------- Microsoft.WindowsDesktop.App.Runtime.win-arm64 | >= 8.0.0, <= 8.0.29 | 8.0.30 Microsoft.WindowsDesktop.App.Runtime.win-x64 | >= 8.0.0, <= 8.0.29 | 8.0.30 Microsoft.WindowsDesktop.App.Runtime.win-x86 | >= 8.0.0, <= 8.0.29 | 8.0.30

Advisory FAQ

<a name="how-affected"></a>How do I know if I am affected?

If using a package listed in affected packages, an application is exposed to the vulnerability.

<a name="how-fix"></a>How do I fix the issue?

1. To fix the issue please install the latest version of .NET. If users 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 a user's application references the vulnerable package, update the package reference to the patched version. Users can list the versions they have installed by running the dotnet --info command.

Once users 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 users have found a potential security issue in a supported version of .NET, please report…

Out-of-bounds write in .NET allows an unauthorized attacker to execute code locally.

Out-of-bounds write in .NET allows an unauthorized attacker to execute code locally.