CVE-2026-21218

.NET Spoofing Vulnerability

CVE-2026-21218 is fixed in 56 products on 3 platforms, first by aspnetcore-runtime-10.0 10.0.3-0ubuntu1~24.04.1, released February 9, 2026. It is not reported as exploited. Patch Radar priority: High.

HighFixed on 3 platforms
CVSS
7.5
Important
Exploitation
None reported
Exploitation Unlikely
CISA KEV
Not listed
Not in the Known Exploited Vulnerabilities catalog
EPSS
0.0100
62nd percentile

<p>Improper handling of missing special element in .NET allows an unauthorized attacker to perform spoofing over a network.</p>

Where it's fixed

ProductFixed inFixReleased
Microsoft
.NET 10.0 runtime installed on Linux KB5077862 Feb 10, 2026
.NET 10.0 runtime installed on Mac OS KB5077862 Feb 10, 2026
.NET 10.0 runtime installed on Windows KB5077862 Feb 10, 2026
.NET 8.0 runtime installed on Linux KB5077863 Feb 10, 2026
.NET 8.0 runtime installed on Mac OS KB5077863 Feb 10, 2026
.NET 8.0 runtime installed on Windows KB5077863 Feb 10, 2026
.NET 9.0 runtime installed on Linux KB5077864 Feb 10, 2026
.NET 9.0 runtime installed on Mac OS KB5077864 Feb 10, 2026
.NET 9.0 runtime installed on Windows KB5077864 Feb 10, 2026
Windows apps
Microsoft .NET Windows Desktop Runtime 8.0 8.0.30 Microsoft .NET Windows Desktop Runtime 8.0 8.0.30 Jul 23, 2026
Linux
aspnetcore-runtime-10.0 · Ubuntu 24.04.5 LTS (noble) 10.0.3-0ubuntu1~24.04.1 aspnetcore-runtime-10.0 10.0.3-0ubuntu1~24.04.1 Feb 9, 2026
aspnetcore-runtime-10.0 · Ubuntu 25.10 (questing) 10.0.3-0ubuntu1~25.10.1 aspnetcore-runtime-10.0 10.0.3-0ubuntu1~25.10.1 Feb 9, 2026
aspnetcore-runtime-8.0 · Ubuntu 22.04.1 LTS (jammy) 8.0.24-0ubuntu1~22.04.1 aspnetcore-runtime-8.0 8.0.24-0ubuntu1~22.04.1 Feb 9, 2026
aspnetcore-runtime-8.0 · Ubuntu 24.04.5 LTS (noble) 8.0.24-0ubuntu1~24.04.1 aspnetcore-runtime-8.0 8.0.24-0ubuntu1~24.04.1 Feb 9, 2026
aspnetcore-runtime-8.0 · Ubuntu 25.10 (questing) 8.0.24-0ubuntu1~25.10.1 aspnetcore-runtime-8.0 8.0.24-0ubuntu1~25.10.1 Feb 9, 2026
aspnetcore-runtime-9.0 · Ubuntu 25.10 (questing) 9.0.13-0ubuntu1~25.10.1 aspnetcore-runtime-9.0 9.0.13-0ubuntu1~25.10.1 Feb 9, 2026
aspnetcore-runtime-dbg-10.0 · Ubuntu 24.04.5 LTS (noble) 10.0.3-0ubuntu1~24.04.1 aspnetcore-runtime-dbg-10.0 10.0.3-0ubuntu1~24.04.1 Feb 9, 2026
aspnetcore-runtime-dbg-10.0 · Ubuntu 25.10 (questing) 10.0.3-0ubuntu1~25.10.1 aspnetcore-runtime-dbg-10.0 10.0.3-0ubuntu1~25.10.1 Feb 9, 2026
aspnetcore-runtime-dbg-8.0 · Ubuntu 22.04.1 LTS (jammy) 8.0.24-0ubuntu1~22.04.1 aspnetcore-runtime-dbg-8.0 8.0.24-0ubuntu1~22.04.1 Feb 9, 2026
aspnetcore-runtime-dbg-8.0 · Ubuntu 24.04.5 LTS (noble) 8.0.24-0ubuntu1~24.04.1 aspnetcore-runtime-dbg-8.0 8.0.24-0ubuntu1~24.04.1 Feb 9, 2026
aspnetcore-runtime-dbg-8.0 · Ubuntu 25.10 (questing) 8.0.24-0ubuntu1~25.10.1 aspnetcore-runtime-dbg-8.0 8.0.24-0ubuntu1~25.10.1 Feb 9, 2026
aspnetcore-runtime-dbg-9.0 · Ubuntu 25.10 (questing) 9.0.13-0ubuntu1~25.10.1 aspnetcore-runtime-dbg-9.0 9.0.13-0ubuntu1~25.10.1 Feb 9, 2026
aspnetcore-targeting-pack-10.0 · Ubuntu 24.04.5 LTS (noble) 10.0.3-0ubuntu1~24.04.1 aspnetcore-targeting-pack-10.0 10.0.3-0ubuntu1~24.04.1 Feb 9, 2026
aspnetcore-targeting-pack-10.0 · Ubuntu 25.10 (questing) 10.0.3-0ubuntu1~25.10.1 aspnetcore-targeting-pack-10.0 10.0.3-0ubuntu1~25.10.1 Feb 9, 2026
aspnetcore-targeting-pack-8.0 · Ubuntu 22.04.1 LTS (jammy) 8.0.24-0ubuntu1~22.04.1 aspnetcore-targeting-pack-8.0 8.0.24-0ubuntu1~22.04.1 Feb 9, 2026
aspnetcore-targeting-pack-8.0 · Ubuntu 24.04.5 LTS (noble) 8.0.24-0ubuntu1~24.04.1 aspnetcore-targeting-pack-8.0 8.0.24-0ubuntu1~24.04.1 Feb 9, 2026
aspnetcore-targeting-pack-8.0 · Ubuntu 25.10 (questing) 8.0.24-0ubuntu1~25.10.1 aspnetcore-targeting-pack-8.0 8.0.24-0ubuntu1~25.10.1 Feb 9, 2026
aspnetcore-targeting-pack-9.0 · Ubuntu 25.10 (questing) 9.0.13-0ubuntu1~25.10.1 aspnetcore-targeting-pack-9.0 9.0.13-0ubuntu1~25.10.1 Feb 9, 2026
dotnet-apphost-pack-10.0 · Ubuntu 24.04.5 LTS (noble) 10.0.3-0ubuntu1~24.04.1 dotnet-apphost-pack-10.0 10.0.3-0ubuntu1~24.04.1 Feb 9, 2026
dotnet-apphost-pack-10.0 · Ubuntu 25.10 (questing) 10.0.3-0ubuntu1~25.10.1 dotnet-apphost-pack-10.0 10.0.3-0ubuntu1~25.10.1 Feb 9, 2026
dotnet-apphost-pack-8.0 · Ubuntu 22.04.1 LTS (jammy) 8.0.24-0ubuntu1~22.04.1 dotnet-apphost-pack-8.0 8.0.24-0ubuntu1~22.04.1 Feb 9, 2026
dotnet-apphost-pack-8.0 · Ubuntu 24.04.5 LTS (noble) 8.0.24-0ubuntu1~24.04.1 dotnet-apphost-pack-8.0 8.0.24-0ubuntu1~24.04.1 Feb 9, 2026
dotnet-apphost-pack-8.0 · Ubuntu 25.10 (questing) 8.0.24-0ubuntu1~25.10.1 dotnet-apphost-pack-8.0 8.0.24-0ubuntu1~25.10.1 Feb 9, 2026
dotnet-apphost-pack-9.0 · Ubuntu 25.10 (questing) 9.0.13-0ubuntu1~25.10.1 dotnet-apphost-pack-9.0 9.0.13-0ubuntu1~25.10.1 Feb 9, 2026
dotnet-host-10.0 · Ubuntu 24.04.5 LTS (noble) 10.0.3-0ubuntu1~24.04.1 dotnet-host-10.0 10.0.3-0ubuntu1~24.04.1 Feb 9, 2026
dotnet-host-10.0 · Ubuntu 25.10 (questing) 10.0.3-0ubuntu1~25.10.1 dotnet-host-10.0 10.0.3-0ubuntu1~25.10.1 Feb 9, 2026
dotnet-host-8.0 · Ubuntu 22.04.1 LTS (jammy) 8.0.24-0ubuntu1~22.04.1 dotnet-host-8.0 8.0.24-0ubuntu1~22.04.1 Feb 9, 2026
dotnet-host-8.0 · Ubuntu 24.04.5 LTS (noble) 8.0.24-0ubuntu1~24.04.1 dotnet-host-8.0 8.0.24-0ubuntu1~24.04.1 Feb 9, 2026
dotnet-host-8.0 · Ubuntu 25.10 (questing) 8.0.24-0ubuntu1~25.10.1 dotnet-host-8.0 8.0.24-0ubuntu1~25.10.1 Feb 9, 2026
dotnet-host-9.0 · Ubuntu 25.10 (questing) 9.0.13-0ubuntu1~25.10.1 dotnet-host-9.0 9.0.13-0ubuntu1~25.10.1 Feb 9, 2026
dotnet-hostfxr-10.0 · Ubuntu 24.04.5 LTS (noble) 10.0.3-0ubuntu1~24.04.1 dotnet-hostfxr-10.0 10.0.3-0ubuntu1~24.04.1 Feb 9, 2026
dotnet-hostfxr-10.0 · Ubuntu 25.10 (questing) 10.0.3-0ubuntu1~25.10.1 dotnet-hostfxr-10.0 10.0.3-0ubuntu1~25.10.1 Feb 9, 2026
dotnet-hostfxr-8.0 · Ubuntu 22.04.1 LTS (jammy) 8.0.24-0ubuntu1~22.04.1 dotnet-hostfxr-8.0 8.0.24-0ubuntu1~22.04.1 Feb 9, 2026
dotnet-hostfxr-8.0 · Ubuntu 24.04.5 LTS (noble) 8.0.24-0ubuntu1~24.04.1 dotnet-hostfxr-8.0 8.0.24-0ubuntu1~24.04.1 Feb 9, 2026
dotnet-hostfxr-8.0 · Ubuntu 25.10 (questing) 8.0.24-0ubuntu1~25.10.1 dotnet-hostfxr-8.0 8.0.24-0ubuntu1~25.10.1 Feb 9, 2026
dotnet-hostfxr-9.0 · Ubuntu 25.10 (questing) 9.0.13-0ubuntu1~25.10.1 dotnet-hostfxr-9.0 9.0.13-0ubuntu1~25.10.1 Feb 9, 2026
dotnet-runtime-10.0 · Ubuntu 24.04.5 LTS (noble) 10.0.3-0ubuntu1~24.04.1 dotnet-runtime-10.0 10.0.3-0ubuntu1~24.04.1 Feb 9, 2026
dotnet-runtime-10.0 · Ubuntu 25.10 (questing) 10.0.3-0ubuntu1~25.10.1 dotnet-runtime-10.0 10.0.3-0ubuntu1~25.10.1 Feb 9, 2026
dotnet-runtime-8.0 · Ubuntu 22.04.1 LTS (jammy) 8.0.24-0ubuntu1~22.04.1 dotnet-runtime-8.0 8.0.24-0ubuntu1~22.04.1 Feb 9, 2026
dotnet-runtime-8.0 · Ubuntu 24.04.5 LTS (noble) 8.0.24-0ubuntu1~24.04.1 dotnet-runtime-8.0 8.0.24-0ubuntu1~24.04.1 Feb 9, 2026
dotnet-runtime-8.0 · Ubuntu 25.10 (questing) 8.0.24-0ubuntu1~25.10.1 dotnet-runtime-8.0 8.0.24-0ubuntu1~25.10.1 Feb 9, 2026
dotnet-runtime-9.0 · Ubuntu 25.10 (questing) 9.0.13-0ubuntu1~25.10.1 dotnet-runtime-9.0 9.0.13-0ubuntu1~25.10.1 Feb 9, 2026
dotnet-runtime-dbg-10.0 · Ubuntu 24.04.5 LTS (noble) 10.0.3-0ubuntu1~24.04.1 dotnet-runtime-dbg-10.0 10.0.3-0ubuntu1~24.04.1 Feb 9, 2026
dotnet-runtime-dbg-10.0 · Ubuntu 25.10 (questing) 10.0.3-0ubuntu1~25.10.1 dotnet-runtime-dbg-10.0 10.0.3-0ubuntu1~25.10.1 Feb 9, 2026
dotnet-runtime-dbg-8.0 · Ubuntu 22.04.1 LTS (jammy) 8.0.24-0ubuntu1~22.04.1 dotnet-runtime-dbg-8.0 8.0.24-0ubuntu1~22.04.1 Feb 9, 2026
dotnet-runtime-dbg-8.0 · Ubuntu 24.04.5 LTS (noble) 8.0.24-0ubuntu1~24.04.1 dotnet-runtime-dbg-8.0 8.0.24-0ubuntu1~24.04.1 Feb 9, 2026
dotnet-runtime-dbg-8.0 · Ubuntu 25.10 (questing) 8.0.24-0ubuntu1~25.10.1 dotnet-runtime-dbg-8.0 8.0.24-0ubuntu1~25.10.1 Feb 9, 2026
dotnet-runtime-dbg-9.0 · Ubuntu 25.10 (questing) 9.0.13-0ubuntu1~25.10.1 dotnet-runtime-dbg-9.0 9.0.13-0ubuntu1~25.10.1 Feb 9, 2026
dotnet-sdk-10.0 · Ubuntu 24.04.5 LTS (noble) 10.0.103-0ubuntu1~24.04.1 dotnet-sdk-10.0 10.0.103-0ubuntu1~24.04.1 Feb 9, 2026
dotnet-sdk-10.0 · Ubuntu 25.10 (questing) 10.0.103-0ubuntu1~25.10.1 dotnet-sdk-10.0 10.0.103-0ubuntu1~25.10.1 Feb 9, 2026
dotnet-sdk-10.0-source-built-artifacts · Ubuntu 24.04.5 LTS (noble) 10.0.103-0ubuntu1~24.04.1 dotnet-sdk-10.0-source-built-artifacts 10.0.103-0ubuntu1~24.04.1 Feb 9, 2026
dotnet-sdk-10.0-source-built-artifacts · Ubuntu 25.10 (questing) 10.0.103-0ubuntu1~25.10.1 dotnet-sdk-10.0-source-built-artifacts 10.0.103-0ubuntu1~25.10.1 Feb 9, 2026
dotnet-sdk-8.0 · Ubuntu 22.04.1 LTS (jammy) 8.0.124-0ubuntu1~22.04.1 dotnet-sdk-8.0 8.0.124-0ubuntu1~22.04.1 Feb 9, 2026
dotnet-sdk-8.0 · Ubuntu 24.04.5 LTS (noble) 8.0.124-0ubuntu1~24.04.1 dotnet-sdk-8.0 8.0.124-0ubuntu1~24.04.1 Feb 9, 2026
dotnet-sdk-8.0 · Ubuntu 25.10 (questing) 8.0.124-0ubuntu1~25.10.1 dotnet-sdk-8.0 8.0.124-0ubuntu1~25.10.1 Feb 9, 2026
dotnet-sdk-8.0-source-built-artifacts · Ubuntu 22.04.1 LTS (jammy) 8.0.124-0ubuntu1~22.04.1 dotnet-sdk-8.0-source-built-artifacts 8.0.124-0ubuntu1~22.04.1 Feb 9, 2026
dotnet-sdk-8.0-source-built-artifacts · Ubuntu 24.04.5 LTS (noble) 8.0.124-0ubuntu1~24.04.1 dotnet-sdk-8.0-source-built-artifacts 8.0.124-0ubuntu1~24.04.1 Feb 9, 2026
dotnet-sdk-8.0-source-built-artifacts · Ubuntu 25.10 (questing) 8.0.124-0ubuntu1~25.10.1 dotnet-sdk-8.0-source-built-artifacts 8.0.124-0ubuntu1~25.10.1 Feb 9, 2026
dotnet-sdk-9.0 · Ubuntu 25.10 (questing) 9.0.114-0ubuntu1~25.10.1 dotnet-sdk-9.0 9.0.114-0ubuntu1~25.10.1 Feb 9, 2026
dotnet-sdk-9.0-source-built-artifacts · Ubuntu 25.10 (questing) 9.0.114-0ubuntu1~25.10.1 dotnet-sdk-9.0-source-built-artifacts 9.0.114-0ubuntu1~25.10.1 Feb 9, 2026
dotnet-sdk-aot-10.0 · Ubuntu 24.04.5 LTS (noble) 10.0.103-0ubuntu1~24.04.1 dotnet-sdk-aot-10.0 10.0.103-0ubuntu1~24.04.1 Feb 9, 2026
dotnet-sdk-aot-10.0 · Ubuntu 25.10 (questing) 10.0.103-0ubuntu1~25.10.1 dotnet-sdk-aot-10.0 10.0.103-0ubuntu1~25.10.1 Feb 9, 2026
dotnet-sdk-aot-9.0 · Ubuntu 25.10 (questing) 9.0.114-0ubuntu1~25.10.1 dotnet-sdk-aot-9.0 9.0.114-0ubuntu1~25.10.1 Feb 9, 2026
dotnet-sdk-dbg-10.0 · Ubuntu 24.04.5 LTS (noble) 10.0.103-0ubuntu1~24.04.1 dotnet-sdk-dbg-10.0 10.0.103-0ubuntu1~24.04.1 Feb 9, 2026
dotnet-sdk-dbg-10.0 · Ubuntu 25.10 (questing) 10.0.103-0ubuntu1~25.10.1 dotnet-sdk-dbg-10.0 10.0.103-0ubuntu1~25.10.1 Feb 9, 2026
dotnet-sdk-dbg-8.0 · Ubuntu 22.04.1 LTS (jammy) 8.0.124-0ubuntu1~22.04.1 dotnet-sdk-dbg-8.0 8.0.124-0ubuntu1~22.04.1 Feb 9, 2026
dotnet-sdk-dbg-8.0 · Ubuntu 24.04.5 LTS (noble) 8.0.124-0ubuntu1~24.04.1 dotnet-sdk-dbg-8.0 8.0.124-0ubuntu1~24.04.1 Feb 9, 2026
dotnet-sdk-dbg-8.0 · Ubuntu 25.10 (questing) 8.0.124-0ubuntu1~25.10.1 dotnet-sdk-dbg-8.0 8.0.124-0ubuntu1~25.10.1 Feb 9, 2026
dotnet-sdk-dbg-9.0 · Ubuntu 25.10 (questing) 9.0.114-0ubuntu1~25.10.1 dotnet-sdk-dbg-9.0 9.0.114-0ubuntu1~25.10.1 Feb 9, 2026
dotnet-targeting-pack-10.0 · Ubuntu 24.04.5 LTS (noble) 10.0.3-0ubuntu1~24.04.1 dotnet-targeting-pack-10.0 10.0.3-0ubuntu1~24.04.1 Feb 9, 2026
dotnet-targeting-pack-10.0 · Ubuntu 25.10 (questing) 10.0.3-0ubuntu1~25.10.1 dotnet-targeting-pack-10.0 10.0.3-0ubuntu1~25.10.1 Feb 9, 2026
dotnet-targeting-pack-8.0 · Ubuntu 22.04.1 LTS (jammy) 8.0.24-0ubuntu1~22.04.1 dotnet-targeting-pack-8.0 8.0.24-0ubuntu1~22.04.1 Feb 9, 2026
dotnet-targeting-pack-8.0 · Ubuntu 24.04.5 LTS (noble) 8.0.24-0ubuntu1~24.04.1 dotnet-targeting-pack-8.0 8.0.24-0ubuntu1~24.04.1 Feb 9, 2026
dotnet-targeting-pack-8.0 · Ubuntu 25.10 (questing) 8.0.24-0ubuntu1~25.10.1 dotnet-targeting-pack-8.0 8.0.24-0ubuntu1~25.10.1 Feb 9, 2026
dotnet-targeting-pack-9.0 · Ubuntu 25.10 (questing) 9.0.13-0ubuntu1~25.10.1 dotnet-targeting-pack-9.0 9.0.13-0ubuntu1~25.10.1 Feb 9, 2026
dotnet-templates-10.0 · Ubuntu 24.04.5 LTS (noble) 10.0.103-0ubuntu1~24.04.1 dotnet-templates-10.0 10.0.103-0ubuntu1~24.04.1 Feb 9, 2026
dotnet-templates-10.0 · Ubuntu 25.10 (questing) 10.0.103-0ubuntu1~25.10.1 dotnet-templates-10.0 10.0.103-0ubuntu1~25.10.1 Feb 9, 2026
dotnet-templates-8.0 · Ubuntu 22.04.1 LTS (jammy) 8.0.124-0ubuntu1~22.04.1 dotnet-templates-8.0 8.0.124-0ubuntu1~22.04.1 Feb 9, 2026
dotnet-templates-8.0 · Ubuntu 24.04.5 LTS (noble) 8.0.124-0ubuntu1~24.04.1 dotnet-templates-8.0 8.0.124-0ubuntu1~24.04.1 Feb 9, 2026
dotnet-templates-8.0 · Ubuntu 25.10 (questing) 8.0.124-0ubuntu1~25.10.1 dotnet-templates-8.0 8.0.124-0ubuntu1~25.10.1 Feb 9, 2026
dotnet-templates-9.0 · Ubuntu 25.10 (questing) 9.0.114-0ubuntu1~25.10.1 dotnet-templates-9.0 9.0.114-0ubuntu1~25.10.1 Feb 9, 2026
dotnet10 · Ubuntu 24.04.5 LTS (noble) 10.0.103-10.0.3-0ubuntu1~24.04.1 dotnet10 10.0.103-10.0.3-0ubuntu1~24.04.1 Feb 9, 2026
dotnet10 · Ubuntu 25.10 (questing) 10.0.103-10.0.3-0ubuntu1~25.10.1 dotnet10 10.0.103-10.0.3-0ubuntu1~25.10.1 Feb 9, 2026
dotnet8 · Ubuntu 22.04.1 LTS (jammy) 8.0.124-8.0.24-0ubuntu1~22.04.1 dotnet8 8.0.124-8.0.24-0ubuntu1~22.04.1 Feb 9, 2026
dotnet8 · Ubuntu 24.04.5 LTS (noble) 8.0.124-8.0.24-0ubuntu1~24.04.1 dotnet8 8.0.124-8.0.24-0ubuntu1~24.04.1 Feb 9, 2026
dotnet8 · Ubuntu 25.10 (questing) 8.0.124-8.0.24-0ubuntu1~25.10.1 dotnet8 8.0.124-8.0.24-0ubuntu1~25.10.1 Feb 9, 2026
dotnet9 · Ubuntu 25.10 (questing) 9.0.114-9.0.13-0ubuntu1~25.10.1 dotnet9 9.0.114-9.0.13-0ubuntu1~25.10.1 Feb 9, 2026
netstandard-targeting-pack-2.1-8.0 · Ubuntu 22.04.1 LTS (jammy) 8.0.124-0ubuntu1~22.04.1 netstandard-targeting-pack-2.1-8.0 8.0.124-0ubuntu1~22.04.1 Feb 9, 2026
netstandard-targeting-pack-2.1-8.0 · Ubuntu 24.04.5 LTS (noble) 8.0.124-0ubuntu1~24.04.1 netstandard-targeting-pack-2.1-8.0 8.0.124-0ubuntu1~24.04.1 Feb 9, 2026
netstandard-targeting-pack-2.1-8.0 · Ubuntu 25.10 (questing) 8.0.124-0ubuntu1~25.10.1 netstandard-targeting-pack-2.1-8.0 8.0.124-0ubuntu1~25.10.1 Feb 9, 2026
netstandard-targeting-pack-2.1-9.0 · Ubuntu 25.10 (questing) 9.0.114-0ubuntu1~25.10.1 netstandard-targeting-pack-2.1-9.0 9.0.114-0ubuntu1~25.10.1 Feb 9, 2026

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