# CVE-2026-70194: .NET TLS client certificate verification bypass

Source: https://junglewise.ai/threats/cve-2026-70194-microsoft-security-advisory-net-and-visual-studio-security  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-13. Updated: 2026-10-13  
License: CC BY 4.0 with a link back

CVE-2026-70194 · Severity: medium · CVSS 6.5 · Published 2026-10-13

.NET 11 implements post-handshake TLS client authentication as part of mutual-authentication security controls. A flaw in System.Net.Security fails to properly verify client certificates in certain scenarios, allowing an attacker to bypass mutual-authentication requirements and communicate without providing valid credentials.

Technologies: [Microsoft .Net](https://junglewise.ai/threats/technologies/microsoft-net), [Microsoft.NetCore.App.Runtime.linux-arm (NuGet)](https://junglewise.ai/threats/technologies/microsoft-netcore-app-runtime-linux-arm), [Microsoft.NetCore.App.Runtime.linux-arm64 (NuGet)](https://junglewise.ai/threats/technologies/microsoft-netcore-app-runtime-linux-arm64), [Microsoft.NetCore.App.Runtime.linux-musl-arm (NuGet)](https://junglewise.ai/threats/technologies/microsoft-netcore-app-runtime-linux-musl-arm), [Microsoft.NetCore.App.Runtime.linux-musl-arm64 (NuGet)](https://junglewise.ai/threats/technologies/microsoft-netcore-app-runtime-linux-musl-arm64), [Microsoft.NetCore.App.Runtime.linux-musl-x64 (NuGet)](https://junglewise.ai/threats/technologies/microsoft-netcore-app-runtime-linux-musl-x64), [Microsoft.NetCore.App.Runtime.linux-x64 (NuGet)](https://junglewise.ai/threats/technologies/microsoft-netcore-app-runtime-linux-x64), [Microsoft.NetCore.App.Runtime.osx-arm64 (NuGet)](https://junglewise.ai/threats/technologies/microsoft-netcore-app-runtime-osx-arm64), [Microsoft.NetCore.App.Runtime.osx-x64 (NuGet)](https://junglewise.ai/threats/technologies/microsoft-netcore-app-runtime-osx-x64). Vendors: [Microsoft](https://junglewise.ai/threats/vendors/microsoft), [NuGet](https://junglewise.ai/threats/vendors/nuget).

## Quick answers

**Is CVE-2026-70194 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-70194 being exploited in the wild.

**How severe is CVE-2026-70194?** Medium severity, with a CVSS score of 6.5, published 13 October 2026.

**Which products and versions are affected?** Microsoft .Net 11.0.0-preview.1 through 11.0.0-rc.1; Microsoft.NetCore.App.Runtime.linux-arm (NuGet) >= 11.0.0-preview.1, <= 11.0.0-rc.1, ECOSYSTEM:introduced=11.0.0-preview.1,fixed=11.0.0-rc.2; Microsoft.NetCore.App.Runtime.linux-arm64 (NuGet) >= 11.0.0-preview.1, <= 11.0.0-rc.1, ECOSYSTEM:introduced=11.0.0-preview.1,fixed=11.0.0-rc.2; Microsoft.NetCore.App.Runtime.linux-musl-arm (NuGet) >= 11.0.0-preview.1, <= 11.0.0-rc.1, ECOSYSTEM:introduced=11.0.0-preview.1,fixed=11.0.0-rc.2; and 5 more.

**Is there a fix for CVE-2026-70194?** Yes. Microsoft.NetCore.App.Runtime.linux-arm (NuGet): upgrade to 11.0.0-rc.2 or later; Microsoft.NetCore.App.Runtime.linux-arm64 (NuGet): upgrade to 11.0.0-rc.2 or later; Microsoft.NetCore.App.Runtime.linux-musl-arm (NuGet): upgrade to 11.0.0-rc.2 or later; Microsoft.NetCore.App.Runtime.linux-musl-arm64 (NuGet): upgrade to 11.0.0-rc.2 or later; Microsoft.NetCore.App.Runtime.linux-musl-x64 (NuGet): upgrade to 11.0.0-rc.2 or later; Microsoft.NetCore.App.Runtime.linux-x64 (NuGet): upgrade to 11.0.0-rc.2 or later; Microsoft.NetCore.App.Runtime.osx-arm64 (NuGet): upgrade to 11.0.0-rc.2 or later; Microsoft.NetCore.App.Runtime.osx-x64 (NuGet): upgrade to 11.0.0-rc.2 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-70194 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-70194?** Check whether you run Microsoft .Net, Microsoft.NetCore.App.Runtime.linux-arm (NuGet), Microsoft.NetCore.App.Runtime.linux-arm64 (NuGet) or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Microsoft.NetCore.App.Runtime.linux-arm (NuGet): upgrade to 11.0.0-rc.2 or later

  ```sh
  dotnet add package Microsoft.NetCore.App.Runtime.linux-arm --version 11.0.0-rc.2
  ```

- Microsoft.NetCore.App.Runtime.linux-arm64 (NuGet): upgrade to 11.0.0-rc.2 or later

  ```sh
  dotnet add package Microsoft.NetCore.App.Runtime.linux-arm64 --version 11.0.0-rc.2
  ```

- Microsoft.NetCore.App.Runtime.linux-musl-arm (NuGet): upgrade to 11.0.0-rc.2 or later

  ```sh
  dotnet add package Microsoft.NetCore.App.Runtime.linux-musl-arm --version 11.0.0-rc.2
  ```

- Microsoft.NetCore.App.Runtime.linux-musl-arm64 (NuGet): upgrade to 11.0.0-rc.2 or later

  ```sh
  dotnet add package Microsoft.NetCore.App.Runtime.linux-musl-arm64 --version 11.0.0-rc.2
  ```

- Microsoft.NetCore.App.Runtime.linux-musl-x64 (NuGet): upgrade to 11.0.0-rc.2 or later

  ```sh
  dotnet add package Microsoft.NetCore.App.Runtime.linux-musl-x64 --version 11.0.0-rc.2
  ```

- Microsoft.NetCore.App.Runtime.linux-x64 (NuGet): upgrade to 11.0.0-rc.2 or later

  ```sh
  dotnet add package Microsoft.NetCore.App.Runtime.linux-x64 --version 11.0.0-rc.2
  ```

- Microsoft.NetCore.App.Runtime.osx-arm64 (NuGet): upgrade to 11.0.0-rc.2 or later

  ```sh
  dotnet add package Microsoft.NetCore.App.Runtime.osx-arm64 --version 11.0.0-rc.2
  ```

- Microsoft.NetCore.App.Runtime.osx-x64 (NuGet): upgrade to 11.0.0-rc.2 or later

  ```sh
  dotnet add package Microsoft.NetCore.App.Runtime.osx-x64 --version 11.0.0-rc.2
  ```


## Technical details

The vulnerability is an improper certificate validation flaw (CWE-295) in .NET 11's System.Net.Security library affecting post-handshake TLS client authentication. It allows an attacker on the network to bypass mutual-authentication requirements by presenting an invalid or missing client certificate that fails to be verified. A fix is available in version 11.0.0-rc.2 and later.

## Affected products

- Microsoft .NET 11.0.0-preview.1 through 11.0.0-rc.1

## Identifiers

- CVE-2026-70194
- GHSA-fqpq-cx42-9jmm

## Timeline

- 2026-10-13: disclosed

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