Description
Not failing securely ('failing open') in .NET allows an unauthorized attacker to bypass a security feature over a network.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Microsoft | .NET 11.0 installed on Linux | 11.0.0-preview.1 – < 11.0.0 | 11.0.0 |
| Microsoft | .NET 11.0 installed on Mac OS | 11.0.0-preview.1 – < 11.0.0 | 11.0.0 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | dotnet10 | 10.0.115-10.0.15-0ubuntu1~26.10.1 | USN-9042-1 |
| Ubuntu 26.10 | dotnet11 | 11.0.100-11.0.0-0ubuntu1~26.10.1 | USN-9042-1 |
| Ubuntu 26.04 LTS | dotnet10 | 10.0.115-10.0.15-0ubuntu1~26.04.1 | USN-9042-1 |
| Ubuntu 24.04 LTS | dotnet10 | 10.0.115-10.0.15-0ubuntu1~24.04.1 | USN-9042-1 |
| Ubuntu 24.04 LTS | dotnet8 | 8.0.134-8.0.34-0ubuntu1~24.04.1 | USN-9042-1 |
| Ubuntu 22.04 LTS | dotnet7 | No fix yet | — |
| Ubuntu 22.04 LTS | dotnet8 | 8.0.134-8.0.34-0ubuntu1~22.04.1 | USN-9042-1 |
Advisories 4
- USN-9042-1 dotnet8, dotnet10, dotnet11 vulnerabilities Ubuntu Security Notices (USN) · Nov 13, 2026
- WID-SEC-2026-4481 Microsoft Developer Tools: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 11, 2026
- MSRC-CVE-2026-118746 .NET Security Feature Bypass Vulnerability Microsoft Security Response Center · Nov 11, 2026
- NCSC-2026-0473 Kwetsbaarheden verholpen in Microsoft Developer Tools NCSC-NL (Netherlands) · Nov 10, 2026
References
- .NET Security Feature Bypass Vulnerability vendor-advisory patch