USN-8420-1: .NET vulnerabilities

Publication date

11 June 2026

Overview

Several security issues were fixed in .NET.


Packages

  • dotnet10 - .NET CLI tools and runtime
  • dotnet8 - .NET CLI tools and runtime
  • dotnet9 - .NET CLI tools and runtime

Details

It was discovered that .NET did not properly handle link resolution before
file access. A local attacker could use this issue to perform unauthorized
file tampering and write arbitrary files outside of the intended extraction
directory. (CVE-2026-45491)

It was discovered that .NET did not properly handle deeply-nested
MessagePack arrays. An attacker could use this to cause .NET to consume
excessive resources, resulting in a denial of service. (CVE-2026-45591)

It was discovered that .NET did not properly handle link resolution before
file access. A local attacker could use this issue to perform unauthorized
file tampering and write arbitrary files outside of the intended extraction
directory. (CVE-2026-45491)

It was discovered that .NET did not properly handle deeply-nested
MessagePack arrays. An attacker could use this to cause .NET to consume
excessive resources, resulting in a denial of service. (CVE-2026-45591)

Update instructions

In general, a standard system update will make all the necessary changes.

Learn more about how to get the fixes.

The problem can be corrected by updating your system to the following package versions:

Ubuntu Release Package Version
26.04 LTS resolute aspnetcore-runtime-10.0 –  10.0.9-0ubuntu1~26.04.1
dotnet-host-10.0 –  10.0.9-0ubuntu1~26.04.1
dotnet-hostfxr-10.0 –  10.0.9-0ubuntu1~26.04.1
dotnet-runtime-10.0 –  10.0.9-0ubuntu1~26.04.1
dotnet-sdk-10.0 –  10.0.109-0ubuntu1~26.04.1
dotnet-sdk-aot-10.0 –  10.0.109-0ubuntu1~26.04.1
dotnet-sdk-dbg-10.0 –  10.0.109-0ubuntu1~26.04.1
dotnet10 –  10.0.109-10.0.9-0ubuntu1~26.04.1
25.10 questing aspnetcore-runtime-10.0 –  10.0.9-0ubuntu1~25.10.1
aspnetcore-runtime-8.0 –  8.0.28-0ubuntu1~25.10.1
aspnetcore-runtime-9.0 –  9.0.17-0ubuntu1~25.10.1
dotnet-host-10.0 –  10.0.9-0ubuntu1~25.10.1
dotnet-host-8.0 –  8.0.28-0ubuntu1~25.10.1
dotnet-host-9.0 –  9.0.17-0ubuntu1~25.10.1
dotnet-hostfxr-10.0 –  10.0.9-0ubuntu1~25.10.1
dotnet-hostfxr-8.0 –  8.0.28-0ubuntu1~25.10.1
dotnet-hostfxr-9.0 –  9.0.17-0ubuntu1~25.10.1
dotnet-runtime-10.0 –  10.0.9-0ubuntu1~25.10.1
dotnet-runtime-8.0 –  8.0.28-0ubuntu1~25.10.1
dotnet-runtime-9.0 –  9.0.17-0ubuntu1~25.10.1
dotnet-sdk-10.0 –  10.0.109-0ubuntu1~25.10.1
dotnet-sdk-8.0 –  8.0.128-0ubuntu1~25.10.1
dotnet-sdk-9.0 –  9.0.118-0ubuntu1~25.10.1
dotnet-sdk-aot-10.0 –  10.0.109-0ubuntu1~25.10.1
dotnet-sdk-aot-9.0 –  9.0.118-0ubuntu1~25.10.1
dotnet-sdk-dbg-10.0 –  10.0.109-0ubuntu1~25.10.1
dotnet-sdk-dbg-9.0 –  9.0.118-0ubuntu1~25.10.1
dotnet10 –  10.0.109-10.0.9-0ubuntu1~25.10.1
dotnet8 –  8.0.128-8.0.28-0ubuntu1~25.10.1
dotnet9 –  9.0.118-9.0.17-0ubuntu1~25.10.1
24.04 LTS noble aspnetcore-runtime-10.0 –  10.0.9-0ubuntu1~24.04.1
aspnetcore-runtime-8.0 –  8.0.28-0ubuntu1~24.04.1
dotnet-host-10.0 –  10.0.9-0ubuntu1~24.04.1
dotnet-host-8.0 –  8.0.28-0ubuntu1~24.04.1
dotnet-hostfxr-10.0 –  10.0.9-0ubuntu1~24.04.1
dotnet-hostfxr-8.0 –  8.0.28-0ubuntu1~24.04.1
dotnet-runtime-10.0 –  10.0.9-0ubuntu1~24.04.1
dotnet-runtime-8.0 –  8.0.28-0ubuntu1~24.04.1
dotnet-sdk-10.0 –  10.0.109-0ubuntu1~24.04.1
dotnet-sdk-8.0 –  8.0.128-0ubuntu1~24.04.1
dotnet-sdk-aot-10.0 –  10.0.109-0ubuntu1~24.04.1
dotnet-sdk-dbg-10.0 –  10.0.109-0ubuntu1~24.04.1
dotnet10 –  10.0.109-10.0.9-0ubuntu1~24.04.1
dotnet8 –  8.0.128-8.0.28-0ubuntu1~24.04.1
22.04 LTS jammy aspnetcore-runtime-8.0 –  8.0.28-0ubuntu1~22.04.1
dotnet-host-8.0 –  8.0.28-0ubuntu1~22.04.1
dotnet-hostfxr-8.0 –  8.0.28-0ubuntu1~22.04.1
dotnet-runtime-8.0 –  8.0.28-0ubuntu1~22.04.1
dotnet-sdk-8.0 –  8.0.128-0ubuntu1~22.04.1
dotnet8 –  8.0.128-8.0.28-0ubuntu1~22.04.1

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