CVE-2026-70197

Out-of-bounds write in .NET allows an unauthorized attacker to execute code over a network.

Out-of-bounds write in .NET allows an unauthorized attacker to execute code over a network.

Executive summary

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

On Windows, reusing a SocketAsyncEventArgs instance across IPv4 and IPv6 datagram sockets can retain an undersized cached native address buffer, allowing an unauthenticated out-of-bounds write during ReceiveFromAsync.

Announcement

Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/466

CVSS Details

• Version: 3.1

• Severity: High

• Score: 8.1

• Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

• Weakness: CWE-787 (Out-of-bounds Write)

Affected Platforms

• Platforms: Windows
• Architectures: All

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

The vulnerability affects Microsoft .NET projects that use an affected package version listed below.

Package name | Affected version | Patched version ------------ | ---------------- | --------------- Microsoft.NETCore.App.Runtime.win-arm | >= 8.0.0, < 8.0.33 | 8.0.33 Microsoft.NETCore.App.Runtime.win-arm64 | >= 8.0.0, < 8.0.33 | 8.0.33 Microsoft.NETCore.App.Runtime.win-x64 | >= 8.0.0, < 8.0.33 | 8.0.33 Microsoft.NETCore.App.Runtime.win-x86 | >= 8.0.0, < 8.0.33 | 8.0.33 Microsoft.NETCore.App.Runtime.win-arm | >= 11.0.0-preview.1, <= 11.0.0-rc.1 | 11.0.0-rc.2 Microsoft.NETCore.App.Runtime.win-arm64 | >= 11.0.0-preview.1, <= 11.0.0-rc.1 | 11.0.0-rc.2 Microsoft.NETCore.App.Runtime.win-x64 | >= 11.0.0-preview.1, <= 11.0.0-rc.1 | 11.0.0-rc.2 Microsoft.NETCore.App.Runtime.win-x86 | >= 11.0.0-preview.1, <= 11.0.0-rc.1 | 11.0.0-rc.2 Microsoft.NETCore.App.Runtime.win-arm | >= 9.0.0, <= 9.0.20 | 9.0.21 Microsoft.NETCore.App.Runtime.win-arm64 | >= 9.0.0, <= 9.0.20 | 9.0.21 Microsoft.NETCore.App.Runtime.win-x64 | >= 9.0.0, <= 9.0.20 | 9.0.21 Microsoft.NETCore.App.Runtime.win-x86 | >= 9.0.0, <= 9.0.20 | 9.0.21 Microsoft.NETCore.App.Runtime.win-arm | >= 10.0.0, <= 10.0.12 | 10.0.13 Microsoft.NETCore.App.Runtime.win-arm64 | >= 10.0.0, <= 10.0.12 | 10.0.13 Microsoft.NETCore.App.Runtime.win-x64 | >= 10.0.0, <= 10.0.12 | 10.0.13 Microsoft.NETCore.App.Runtime.win-x86 | >= 10.0.0, <= 10.0.12 | 10.0.13

Advisory FAQ

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

If using a package listed in affected packages, you're 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 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,…

Out-of-bounds write in .NET allows an unauthorized attacker to execute code over a network.

Out-of-bounds write in .NET allows an unauthorized attacker to execute code over a network.

Executive summary

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

On Windows, reusing a SocketAsyncEventArgs instance across IPv4 and IPv6 datagram sockets can retain an undersized cached native address buffer, allowing an unauthenticated out-of-bounds write during ReceiveFromAsync.

Announcement

Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/466

CVSS Details

• Version: 3.1

• Severity: High

• Score: 8.1

• Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

• Weakness: CWE-787 (Out-of-bounds Write)

Affected Platforms

• Platforms: Windows
• Architectures: All

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

The vulnerability affects Microsoft .NET projects that use an affected package version listed below.

Package name | Affected version | Patched version ------------ | ---------------- | --------------- Microsoft.NETCore.App.Runtime.win-arm | >= 8.0.0, < 8.0.33 | 8.0.33 Microsoft.NETCore.App.Runtime.win-arm64 | >= 8.0.0, < 8.0.33 | 8.0.33 Microsoft.NETCore.App.Runtime.win-x64 | >= 8.0.0, < 8.0.33 | 8.0.33 Microsoft.NETCore.App.Runtime.win-x86 | >= 8.0.0, < 8.0.33 | 8.0.33 Microsoft.NETCore.App.Runtime.win-arm | >= 11.0.0-preview.1, <= 11.0.0-rc.1 | 11.0.0-rc.2 Microsoft.NETCore.App.Runtime.win-arm64 | >= 11.0.0-preview.1, <= 11.0.0-rc.1 | 11.0.0-rc.2 Microsoft.NETCore.App.Runtime.win-x64 | >= 11.0.0-preview.1, <= 11.0.0-rc.1 | 11.0.0-rc.2 Microsoft.NETCore.App.Runtime.win-x86 | >= 11.0.0-preview.1, <= 11.0.0-rc.1 | 11.0.0-rc.2 Microsoft.NETCore.App.Runtime.win-arm | >= 9.0.0, <= 9.0.20 | 9.0.21 Microsoft.NETCore.App.Runtime.win-arm64 | >= 9.0.0, <= 9.0.20 | 9.0.21 Microsoft.NETCore.App.Runtime.win-x64 | >= 9.0.0, <= 9.0.20 | 9.0.21 Microsoft.NETCore.App.Runtime.win-x86 | >= 9.0.0, <= 9.0.20 | 9.0.21 Microsoft.NETCore.App.Runtime.win-arm | >= 10.0.0, <= 10.0.12 | 10.0.13 Microsoft.NETCore.App.Runtime.win-arm64 | >= 10.0.0, <= 10.0.12 | 10.0.13 Microsoft.NETCore.App.Runtime.win-x64 | >= 10.0.0, <= 10.0.12 | 10.0.13 Microsoft.NETCore.App.Runtime.win-x86 | >= 10.0.0, <= 10.0.12 | 10.0.13

Advisory FAQ

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

If using a package listed in affected packages, you're 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 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,…

Out-of-bounds write in .NET allows an unauthorized attacker to execute code over a network.