==========================================================================
Ubuntu Security Notice USN-8085-1
March 11, 2026

dotnet8, dotnet9, dotnet10 vulnerabilities
==========================================================================

A security issue affects these releases of Ubuntu and its derivatives:

- 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 the .NET Microsoft.Bcl.Memory NuGet package did not
properly handle certain malformed Base64Url encoded input. An attacker could
possibly use this issue to cause .NET to crash, resulting in a denial of
service. This issue only affected .NET 9.0 and .NET 10.0. (CVE-2026-26127)

Bart\u0142omiej Dach discovered that .NET's SignalR server component did not
properly manage resource consumption when processing certain messages. An
attacker could possibly use this issue to exhaust internal buffers, resulting
in a denial of service. (CVE-2026-26130)

Update instructions:

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

Ubuntu 25.10
  aspnetcore-runtime-10.0         10.0.4-0ubuntu1~25.10.1
  aspnetcore-runtime-8.0          8.0.25-0ubuntu1~25.10.1
  aspnetcore-runtime-9.0          9.0.14-0ubuntu1~25.10.1
  dotnet-host-10.0                10.0.4-0ubuntu1~25.10.1
  dotnet-host-8.0                 8.0.25-0ubuntu1~25.10.1
  dotnet-host-9.0                 9.0.14-0ubuntu1~25.10.1
  dotnet-hostfxr-10.0             10.0.4-0ubuntu1~25.10.1
  dotnet-hostfxr-8.0              8.0.25-0ubuntu1~25.10.1
  dotnet-hostfxr-9.0              9.0.14-0ubuntu1~25.10.1
  dotnet-runtime-10.0             10.0.4-0ubuntu1~25.10.1
  dotnet-runtime-8.0              8.0.25-0ubuntu1~25.10.1
  dotnet-runtime-9.0              9.0.14-0ubuntu1~25.10.1
  dotnet-sdk-10.0                 10.0.104-0ubuntu1~25.10.1
  dotnet-sdk-8.0                  8.0.125-0ubuntu1~25.10.1
  dotnet-sdk-9.0                  9.0.115-0ubuntu1~25.10.1
  dotnet-sdk-aot-10.0             10.0.104-0ubuntu1~25.10.1
  dotnet-sdk-aot-9.0              9.0.115-0ubuntu1~25.10.1
  dotnet10                        10.0.104-10.0.4-0ubuntu1~25.10.1
  dotnet8                         8.0.125-8.0.25-0ubuntu1~25.10.1
  dotnet9                         9.0.115-9.0.14-0ubuntu1~25.10.1

Ubuntu 24.04 LTS
  aspnetcore-runtime-10.0         10.0.4-0ubuntu1~24.04.1
  aspnetcore-runtime-8.0          8.0.25-0ubuntu1~24.04.1
  dotnet-host-10.0                10.0.4-0ubuntu1~24.04.1
  dotnet-host-8.0                 8.0.25-0ubuntu1~24.04.1
  dotnet-hostfxr-10.0             10.0.4-0ubuntu1~24.04.1
  dotnet-hostfxr-8.0              8.0.25-0ubuntu1~24.04.1
  dotnet-runtime-10.0             10.0.4-0ubuntu1~24.04.1
  dotnet-runtime-8.0              8.0.25-0ubuntu1~24.04.1
  dotnet-sdk-10.0                 10.0.104-0ubuntu1~24.04.1
  dotnet-sdk-8.0                  8.0.125-0ubuntu1~24.04.1
  dotnet-sdk-aot-10.0             10.0.104-0ubuntu1~24.04.1
  dotnet10                        10.0.104-10.0.4-0ubuntu1~24.04.1
  dotnet8                         8.0.125-8.0.25-0ubuntu1~24.04.1

Ubuntu 22.04 LTS
  aspnetcore-runtime-8.0          8.0.25-0ubuntu1~22.04.1
  dotnet-host-8.0                 8.0.25-0ubuntu1~22.04.1
  dotnet-hostfxr-8.0              8.0.25-0ubuntu1~22.04.1
  dotnet-runtime-8.0              8.0.25-0ubuntu1~22.04.1
  dotnet-sdk-8.0                  8.0.125-0ubuntu1~22.04.1
  dotnet8                         8.0.125-8.0.25-0ubuntu1~22.04.1

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

References:
  https://ubuntu.com/security/notices/USN-8085-1
  CVE-2026-26127, CVE-2026-26130

Package Information:
  https://launchpad.net/ubuntu/+source/dotnet10/10.0.104-10.0.4-0ubuntu1~25.10.1
  https://launchpad.net/ubuntu/+source/dotnet8/8.0.125-8.0.25-0ubuntu1~25.10.1
  https://launchpad.net/ubuntu/+source/dotnet9/9.0.115-9.0.14-0ubuntu1~25.10.1
  https://launchpad.net/ubuntu/+source/dotnet10/10.0.104-10.0.4-0ubuntu1~24.04.1
  https://launchpad.net/ubuntu/+source/dotnet8/8.0.125-8.0.25-0ubuntu1~24.04.1
  https://launchpad.net/ubuntu/+source/dotnet8/8.0.125-8.0.25-0ubuntu1~22.04.1