--- id: "CVE-2026-70197" kind: "vulnerability" aliases: ["CVE-2026-70197", "GHSA-4mpw-cpwj-hxxj"] title: "Microsoft Security Advisory CVE-2026-70197 - .NET and Visual Studio Remote Code Execution Vulnerability" severity: "high" cvss: 8.100000381469727 epss: 0.006949999835342169 exploited: false status: "open" category: "runtime" products: [{"name": "Microsoft.NETCore.App.Runtime.win-arm64", "fixed": ["8.0.32"], "affected": ">= 8.0.0, <= 8.0.31", "ecosystem": "nuget"}, {"name": "Microsoft.NETCore.App.Runtime.win-x64", "fixed": ["8.0.32"], "affected": ">= 8.0.0, <= 8.0.31", "ecosystem": "nuget"}, {"name": "Microsoft.NETCore.App.Runtime.win-x86", "fixed": ["8.0.32"], "affected": ">= 8.0.0, <= 8.0.31", "ecosystem": "nuget"}, {"name": "Microsoft.NETCore.App.Runtime.win-arm64", "fixed": ["11.0.0-rc.2"], "affected": ">= 11.0.0-preview.1, <= 11.0.0-rc.1", "ecosystem": "nuget"}, {"name": "Microsoft.NETCore.App.Runtime.win-x64", "fixed": ["11.0.0-rc.2"], "affected": ">= 11.0.0-preview.1, <= 11.0.0-rc.1", "ecosystem": "nuget"}, {"name": "Microsoft.NETCore.App.Runtime.win-x86", "fixed": ["11.0.0-rc.2"], "affected": ">= 11.0.0-preview.1, <= 11.0.0-rc.1", "ecosystem": "nuget"}, {"name": "Microsoft.NETCore.App.Runtime.win-arm64", "fixed": ["9.0.21"], "affected": ">= 9.0.0, <= 9.0.20", "ecosystem": "nuget"}, {"name": "Microsoft.NETCore.App.Runtime.win-x64", "fixed": ["9.0.21"], "affected": ">= 9.0.0, <= 9.0.20", "ecosystem": "nuget"}, {"name": "Microsoft.NETCore.App.Runtime.win-x86", "fixed": ["9.0.21"], "affected": ">= 9.0.0, <= 9.0.20", "ecosystem": "nuget"}, {"name": "Microsoft.NETCore.App.Runtime.win-arm64", "fixed": ["10.0.13"], "affected": ">= 10.0.0, <= 10.0.12", "ecosystem": "nuget"}, {"name": "Microsoft.NETCore.App.Runtime.win-x64", "fixed": ["10.0.13"], "affected": ">= 10.0.0, <= 10.0.12", "ecosystem": "nuget"}, {"name": "Microsoft.NETCore.App.Runtime.win-x86", "fixed": ["10.0.13"], "affected": ">= 10.0.0, <= 10.0.12", "ecosystem": "nuget"}] ecosystems: ["nuget"] tags: ["cwe-787", "dotnet", "runtime", "self-contained-apps", "udp-servers", "windows"] not_affected_if: ["default-config-not-applicable", "linux-or-macos-only", "no-udp-receivefromasync"] published_at: "2026-10-13T19:19:33+00:00" first_seen_at: "2026-10-23T19:11:32+00:00" updated_at: "2026-10-23T23:44:52+00:00" sources: [{"source": "ghsa", "url": "https://github.com/advisories/GHSA-4mpw-cpwj-hxxj", "first_seen_at": "2026-10-23T19:11:32+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-70197", "first_seen_at": "2026-10-23T23:44:52+00:00"}] --- # Microsoft Security Advisory CVE-2026-70197 - .NET and Visual Studio Remote Code Execution Vulnerability A bug in .NET's System.Net.Sockets on Windows reuses a too-small cached native address buffer when a SocketAsyncEventArgs is shared between IPv4 and IPv6 datagram sockets, so ReceiveFromAsync can write out of bounds. An unauthenticated remote attacker sending crafted datagrams may trigger memory corruption and potentially code execution. _Summary, check and fix written by a model from the sources; labelled as such._ ## Affected - nuget:Microsoft.NETCore.App.Runtime.win-arm64 affected >= 8.0.0, <= 8.0.31 fixed 8.0.32 - nuget:Microsoft.NETCore.App.Runtime.win-x64 affected >= 8.0.0, <= 8.0.31 fixed 8.0.32 - nuget:Microsoft.NETCore.App.Runtime.win-x86 affected >= 8.0.0, <= 8.0.31 fixed 8.0.32 - nuget:Microsoft.NETCore.App.Runtime.win-arm64 affected >= 11.0.0-preview.1, <= 11.0.0-rc.1 fixed 11.0.0-rc.2 - nuget:Microsoft.NETCore.App.Runtime.win-x64 affected >= 11.0.0-preview.1, <= 11.0.0-rc.1 fixed 11.0.0-rc.2 - nuget:Microsoft.NETCore.App.Runtime.win-x86 affected >= 11.0.0-preview.1, <= 11.0.0-rc.1 fixed 11.0.0-rc.2 - nuget:Microsoft.NETCore.App.Runtime.win-arm64 affected >= 9.0.0, <= 9.0.20 fixed 9.0.21 - nuget:Microsoft.NETCore.App.Runtime.win-x64 affected >= 9.0.0, <= 9.0.20 fixed 9.0.21 - nuget:Microsoft.NETCore.App.Runtime.win-x86 affected >= 9.0.0, <= 9.0.20 fixed 9.0.21 - nuget:Microsoft.NETCore.App.Runtime.win-arm64 affected >= 10.0.0, <= 10.0.12 fixed 10.0.13 - nuget:Microsoft.NETCore.App.Runtime.win-x64 affected >= 10.0.0, <= 10.0.12 fixed 10.0.13 - nuget:Microsoft.NETCore.App.Runtime.win-x86 affected >= 10.0.0, <= 10.0.12 fixed 10.0.13 ## How to check Run dotnet --info and check the installed runtime version against the affected ranges (8.0.0-8.0.31, 9.0.0-9.0.20, 10.0.0-10.0.12, 11.0.0-preview.1 to 11.0.0-rc.1). List NuGet references with dotnet list package and look for Microsoft.NETCore.App.Runtime.win-* in self-contained publish outputs. ## Fix Install the patched .NET runtime: 8.0.32, 9.0.21, 10.0.13, or 11.0.0-rc.2 or later, then restart apps. Recompile and redeploy self-contained Windows applications against a patched runtime. ## Timeline - 2026-10-23T19:11:32+00:00 ghsa https://github.com/advisories/GHSA-4mpw-cpwj-hxxj - 2026-10-23T23:44:52+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-70197 ## From the sources ## 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 ## 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](https://www.nuget.org/packages/Microsoft.NETCore.App.Runtime.win-arm) | >= 8.0.0, <= 8.0.31 | 8.0.32 [Microsoft.NETCore.App.Runtime.win-arm64](https://www.nuget.org/packages/Microsoft.NETCore.App.Runtime.win-arm64) | >= 8.0.0, <= 8.0.31 | 8.0.32 [Microsoft.NETCore.App.Runtime.win-x64](https://www.nuget.org/packages/Microsoft.NETCore.App.Runtime.win-x64) | >= 8.0.0, <= 8.0.31 | 8.0.32 [Microsoft.NETCore.App.Runtime.win-x86](https://www.nuget.org/packages/Microsoft.NETCore.App.Runtime.win-x86) | >= 8.0.0, <= 8.0.31 | 8.0.32 [Microsoft.NETCore.App.Runtime.win-arm](https://www.nuget.org/packages/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](https://www.nuget.org/packages/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](https://www.nuget.org/packages/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](https://www.nuget.org/packages/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](https://www.nuget.org/packages/Microsoft.NETCore.App.Runtime.win-arm) | >= 9.0.0, <= 9.0.20 | 9.0.21 [Microsoft.NETCore.App.Runtime.win-arm64](https://www.nuget.org/packages/Microsoft.NETCore.App.Runtime.win-arm64) | >= 9.0.0, <= 9.0.20 | 9.0.21 [Microsoft.NETCore.App.Runtime.win-x64](https://www.nuget.org/packages/Microsoft.NETCore.App.Runtime.win-x64) | >= 9.0.0, <= 9.0.20 | 9.0.21 [Microsoft.NETCore.App.Runtime.win-x86](https://www.nuget.org/packages/Microsoft.NETCore.App.Runtime.win-x86) | >= 9.0.0, <= 9.0.20 | 9.0.21 [Microsoft.NETCore.App.Runtime.win-arm](https://www.nuget.org/packages/Microsoft.NETCore.App.Runtime.win-arm) | >= 10.0.0, <= 10.0.12 | 10.0.13 [Microsoft.NETCore.App.Runtime.win-arm64](https://www.nuget.org/packages/Microsoft.NETCore.App.Runtime.win-arm64) | >= 10.0.0, <= 10.0.12 | 10.0.13 [Microsoft.NETCore.App.Runtime.win-x64](https://www.nuget.org/packages/Microsoft.NETCore.App.Runtime.win-x64) | >= 10.0.0, <= 10.0.12 | 10.0.13 [Microsoft.NETCore.App.Runtime.win-x86](https://www.nuget.org/packages/Microsoft.NETCore.App.Runtime.win-x86) | >= 10.0.0, <= 10.0.12 | 10.0.13 ## Advisory FAQ ### How do I know if I am affected? If using a package listed in [affected packages](#affected-packages), you're exposed to the vulnerability. ### 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, update the package reference to the patched version. You can list the versions you have installed by running the `dotnet --info` command. 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](https://docs.microsoft.com/dotnet/core/deploying/#self-contained-deployments-scd) targeting any of the impacted versions, these applications are also vulnerable and must be recompiled and redeployed. ## Other Information ### 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](https://msrc.microsoft.com/report/vulnerability/new). Further information can be found in the MSRC [Report an Issue FAQ](https://www.microsoft.com/msrc/faqs-report-an-issue). 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 You can ask questions about this issue on 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. You 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-2026-70197](https://www.cve.org/CVERecord?id=CVE-2026-70197) ### Acknowledgements - Anonymous ### Revisions V1.0 (10/13/2026): Advisory published. --- _Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_