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Ubuntu 25.10: .NET Important Denial of Service & SMTP Issue USN-7822-1

ubuntu
Calendar Grey October 16, 2025
Dist Ubuntu Esm H88
Critical updates for .NET on Ubuntu to mitigate denial of service and SMTP security risks. Act promptly to secure your system.
Several security issues were fixed in .NET

Summary

A security issue affects these releases of Ubuntu and its derivatives: - Ubuntu 25.10 - Ubuntu 25.04 - 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 the creation of temporary build time directories. An attacker could possibly use this issue to cause a denial of service. (CVE-2025-55247) It was discovered that .NET did not properly establish TLS sessions for SMTP server connections. An attacker could use this issue to cause .NET to use unencrypted connections. This issue only affects .NET versions 8.0 and 9.0. (CVE-2025-55248) It was discovered that .NET inconsistently interpreted certain http requests. An attacker could possibly use this to bypass a security feature over a network. (CVE-2025-55315)

Topics%20covered

Topics Covered

security advisory denial of service Ubuntu important dotnet smtp issue

Update Instructions

The problem can be corrected by updating your system to the following package versions: Ubuntu 25.10 aspnetcore-runtime-10.0 10.0.0~rc2-0ubuntu1~25.10.2 aspnetcore-runtime-8.0 8.0.21-0ubuntu1~25.10.1 aspnetcore-runtime-9.0 9.0.10-0ubuntu1~25.10.1 dotnet-host-10.0 10.0.0~rc2-0ubuntu1~25.10.2 dotnet-host-8.0 8.0.21-0ubuntu1~25.10.1 dotnet-host-9.0 9.0.10-0ubuntu1~25.10.1 dotnet-hostfxr-10.0 10.0.0~rc2-0ubuntu1~25.10.2 dotnet-hostfxr-8.0 8.0.21-0ubuntu1~25.10.1 dotnet-hostfxr-9.0 9.0.10-0ubuntu1~25.10.1 dotnet-runtime-10.0 10.0.0~rc2-0ubuntu1~25.10.2 dotnet-runtime-8.0 8.0.21-0ubuntu1~25.10.1 dotnet-runtime-9.0 9.0.10-0ubuntu1~25.10.1 dotnet-sdk-10.0 10.0.100~rc2-0ubuntu1~25.10.2 dotnet-sdk-8.0 8.0.121-0ubuntu1~25.10.1 dotnet-sdk-9.0 9.0.111-0ubuntu1~25.10.1 dotnet-sdk-aot-10.0 10.0.100~rc2-0ubuntu1~25.10.2 dotnet-sdk-aot-9.0 9.0.111-0ubuntu1~25.10.1 dotnet10 10.0.100-10.0.0~rc2-0ubuntu1~25.10.2 dotnet8 8.0.121-8.0.21-0ubuntu1~25.10.1 dotnet9 9.0.111-9.0.10-0ubuntu1~25.10.1 Ubuntu 25.04 aspnetcore-runtime-8.0 8.0.21-0ubuntu1~25.04.1 aspnetcore-runtime-9.0 9.0.10-0ubuntu1~25.04.1 dotnet-host-8.0 8.0.21-0ubuntu1~25.04.1 dotnet-host-9.0 9.0.10-0ubuntu1~25.04.1 dotnet-hostfxr-8.0 8.0.21-0ubuntu1~25.04.1 dotnet-hostfxr-9.0 9.0.10-0ubuntu1~25.04.1 dotnet-runtime-8.0 8.0.21-0ubuntu1~25.04.1 dotnet-runtime-9.0 9.0.10-0ubuntu1~25.04.1 dotnet-sdk-8.0 8.0.121-0ubuntu1~25.04.1 dotnet-sdk-9.0 9.0.111-0ubuntu1~25.04.1 dotnet-sdk-aot-9.0 9.0.111-0ubuntu1~25.04.1 dotnet8 8.0.121-8.0.21-0ubuntu1~25.04.1 dotnet9 9.0.111-9.0.10-0ubuntu1~25.04.1 Ubuntu 24.04 LTS aspnetcore-runtime-8.0 8.0.21-0ubuntu1~24.04.1 dotnet-host-8.0 8.0.21-0ubuntu1~24.04.1 dotnet-hostfxr-8.0 8.0.21-0ubuntu1~24.04.1 dotnet-runtime-8.0 8.0.21-0ubuntu1~24.04.1 dotnet-sdk-8.0 8.0.121-0ubuntu1~24.04.1 dotnet8 8.0.121-8.0.21-0ubuntu1~24.04.1 Ubuntu 22.04 LTS aspnetcore-runtime-8.0 8.0.21-0ubuntu1~22.04.1 dotnet-host-8.0 8.0.21-0ubuntu1~22.04.1 dotnet-hostfxr-8.0 8.0.21-0ubuntu1~22.04.1 dotnet-runtime-8.0 8.0.21-0ubuntu1~22.04.1 dotnet-sdk-8.0 8.0.121-0ubuntu1~22.04.1 dotnet8 8.0.121-8.0.21-0ubuntu1~22.04.1 In general, a standard system update will make all the necessary changes.

References

https://ubuntu.com/security/notices/USN-7822-1

CVE-2025-55247, CVE-2025-55248, CVE-2025-55315

Severity
important
Lowest
Low
Medium
High
Critical

Ubuntu Security Notice USN-7822-1

Topics%20covered

Topics Covered

security advisory denial of service Ubuntu important dotnet smtp issue

Package Information

https://launchpad.net/ubuntu/+source/dotnet10/10.0.100-10.0.0~rc2-0ubuntu1~25.10.2 https://launchpad.net/ubuntu/+source/dotnet8/8.0.121-8.0.21-0ubuntu1~25.10.1 https://launchpad.net/ubuntu/+source/dotnet9/9.0.111-9.0.10-0ubuntu1~25.10.1 https://launchpad.net/ubuntu/+source/dotnet8/8.0.121-8.0.21-0ubuntu1~25.04.1 https://launchpad.net/ubuntu/+source/dotnet9/9.0.111-9.0.10-0ubuntu1~25.04.1 https://launchpad.net/ubuntu/+source/dotnet8/8.0.121-8.0.21-0ubuntu1~24.04.1 https://launchpad.net/ubuntu/+source/dotnet8/8.0.121-8.0.21-0ubuntu1~22.04.1

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