Ubuntu Security Notices USN-8420-1 USN-8420-1: .NET vulnerabilities Publication date 11 June 2026 Overview Several security issues were fixed in .NET. Releases 26.04 LTS 25.10 24.04 LTS 22.04 LTS Open side navigation Close side navigation Packages Details Update instructions References 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 Reduce your security exposure Ubuntu Pro provides ten-year security coverage to 25,000+ packages in Main and Universe repositories, and it is free for up to five machines. Get Ubuntu Pro References CVE-2026-45591 CVE-2026-45491 CVE-2026-45591 CVE-2026-45491