Since May 2020 CoreOS Container Linux is end of life and no longer receives updates. With the upcoming Kubermatic Kubernetes Platform (KKP) 2.16 release, we will no longer support CoreOS Container Linux. In case you still have CoreOS clusters running, you risk to encounter major security liability from defective clusters. Please read this blog post to learn how to migrate your clusters to be able to upgrade to v2.16.
This is a companion discussion topic for the original entry at https://www.kubermatic.com/blog/support-for-coreos-container-linux-has-ended/