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Ubuntu 24.04 LTS USN-8025-2 .NET Critical Bypass CVE-2026-21218

ubuntu
Calendar Grey February 16, 2026
Dist Ubuntu Esm H88
This advisory informs about a critical .NET security issue on Ubuntu 24.04 LTS, enabling potential unauthorized access.
.NET could be made to bypass security features.

Summary

.NET could be made to bypass security features.

Software Description:

- dotnet10: .NET CLI tools and runtime

- dotnet8: .NET CLI tools and runtime

Details:

USN 8025-1 fixed a vulnerability in .NET. This update provides the

corresponding fix for Ubuntu 24.04 LTS.

Original advisory details:

Kevin Jones discovered that the System.Security.Cryptography.Cose

component in .NET did not properly handle certain missing special

elements in input data. An attacker could possibly use this issue to

bypass security checks and gain unauthorized access or perform data

manipulation.

Topics%20covered

Topics Covered

security advisory unauthorized access security issue critical Ubuntu dotnet

Update Instructions

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

Ubuntu 24.04 LTS
  aspnetcore-runtime-10.0         10.0.3-0ubuntu1~24.04.1
  aspnetcore-runtime-8.0          8.0.24-0ubuntu1~24.04.1
  dotnet-host-10.0                10.0.3-0ubuntu1~24.04.1
  dotnet-host-8.0                 8.0.24-0ubuntu1~24.04.1
  dotnet-hostfxr-10.0             10.0.3-0ubuntu1~24.04.1
  dotnet-hostfxr-8.0              8.0.24-0ubuntu1~24.04.1
  dotnet-runtime-10.0             10.0.3-0ubuntu1~24.04.1
  dotnet-runtime-8.0              8.0.24-0ubuntu1~24.04.1
  dotnet-sdk-10.0                 10.0.103-0ubuntu1~24.04.1
  dotnet-sdk-8.0                  8.0.124-0ubuntu1~24.04.1
  dotnet-sdk-aot-10.0             10.0.103-0ubuntu1~24.04.1
  dotnet10                        10.0.103-10.0.3-0ubuntu1~24.04.1
  dotnet8                         8.0.124-8.0.24-0ubuntu1~24.04.1

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

References

https://ubuntu.com/security/notices/USN-8025-2

https://ubuntu.com/security/notices/USN-8025-1

CVE-2026-21218

Severity
critical
Lowest
Low
Medium
High
Critical

Ubuntu Security Notice USN-8025-2

Topics%20covered

Topics Covered

security advisory unauthorized access security issue critical Ubuntu dotnet

Package Information

https://launchpad.net/ubuntu/+source/dotnet10/10.0.103-10.0.3-0ubuntu1~24.04.1
https://launchpad.net/ubuntu/+source/dotnet8/8.0.124-8.0.24-0ubuntu1~24.04.1

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