Microsoft Security Advisory CVE-2026-70194 - .NET and Visual Studio Security Feature Bypass Vulnerability

{
  "id": "67fb0c961ad27746fd72754e1c7d7b04e1ca2bf951a9c526ab960b8b2a8ab950",
  "url": "https://osv.dev/vulnerability/GHSA-fqpq-cx42-9jmm",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Microsoft Security Advisory CVE-2026-70194 - .NET and Visual Studio Security Feature Bypass Vulnerability",
    "summary": "## Executive summary Microsoft is releasing this security advisory to provide information about a vulnerability in System.Net.Security. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability. .NET 11 post-handshake TLS client authentication can fail to verify the client certificate, allowing mutual-authentication requirements to be bypassed. ## Announcement Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/464 ## CVSS Details - **Version:** 3.1 - **Severity:** Moderate - **Score:** 6.5 - **Vector:** `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N` - **Weakness:** CWE-295 (Improper Certificate Validation) ## Affected Platforms - **Platforms:** Linux, macOS - **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.linux-arm](https://www.nuget.org/packages/Microsoft.NETCore.App.Runtime.linux-arm) | >= 11.0.0-preview.1, <= 11.0.0-rc.1 | 11.0.0-rc.2 [Microsoft.NETCore.App.Runtime.linux-arm64](https://www.nuget.org/packages/Microsoft.NETCore.App.Runtime.linux-arm64) | >= 11.0.0-preview.1, <= 11.0.0-rc.1 | 11.0.0-rc.2 [Microsoft.NETCore.App.Runtime.linux-musl-arm](https://www.nuget.org/packages/Microsoft.NETCore.App.Runtime.linux-musl-arm) | >= 11.0.0-preview.1, <",
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      "modified": "2026-10-19T16:30:08.493019642Z",
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      "references": [
        "https://github.com/dotnet/runtime/security/advisories/GHSA-fqpq-cx42-9jmm",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-70194",
        "https://github.com/dotnet/announcements/issues/464",
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        "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-70194"
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  "published_at": "2026-10-13T20:00:42+00:00"
}