The CNFC has been funding security audits of projects since last year. With CoreDNS, Envoy, and Prometheus taken care of, Kubernetes itself recently received the treatment.
The assessment yielded a significant amount of knowledge pertaining to the operation and internals of a Kubernetes cluster. Findings and supporting documentation from the assessment has been made available today, and can be found here.
If you don’t want the full report, the linked announcement lists some of the major takeaways.