========================================================================== Ubuntu Security Notice USN-8420-1 June 11, 2026
dotnet8, dotnet9, dotnet10 vulnerabilities ========================================================================== A security issue affects these releases of Ubuntu and its derivatives: - Ubuntu 26.04 LTS - Ubuntu 25.10 - Ubuntu 24.04 LTS - Ubuntu 22.04 LTS Summary: Several security issues were fixed in .NET. Software Description: - 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) Update instructions: The problem can be corrected by updating your system to the following package versions: Ubuntu 26.04 LTS 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 Ubuntu 25.10 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 Ubuntu 24.04 LTS 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 Ubuntu 22.04 LTS 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 In general, a standard system update will make all the necessary changes. References: https://ubuntu.com/security/notices/USN-8420-1 CVE-2026-45491, CVE-2026-45591 Package Information: https://launchpad.net/ubuntu/+source/dotnet10/10.0.109-10.0.9-0ubuntu1~26.04.1 https://launchpad.net/ubuntu/+source/dotnet10/10.0.109-10.0.9-0ubuntu1~25.10.1 https://launchpad.net/ubuntu/+source/dotnet8/8.0.128-8.0.28-0ubuntu1~25.10.1 https://launchpad.net/ubuntu/+source/dotnet9/9.0.118-9.0.17-0ubuntu1~25.10.1 https://launchpad.net/ubuntu/+source/dotnet10/10.0.109-10.0.9-0ubuntu1~24.04.1 https://launchpad.net/ubuntu/+source/dotnet8/8.0.128-8.0.28-0ubuntu1~24.04.1 https://launchpad.net/ubuntu/+source/dotnet8/8.0.128-8.0.28-0ubuntu1~22.04.1
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