Improper validation of URL redirection in the Kubernetes API server in versions prior to v1.14.0 allows an attacker-controlled Kubelet to redirect API server requests from streaming endpoints to arbitrary hosts. Impacted API servers will follow the redirect as a GET request with client-certificate credentials for authenticating to the Kubelet.

Cloud Native Computing Foundation (CNCF) CNI (Container Networking Interface) 0.7.4 has a network firewall misconfiguration which affects Kubernetes. The CNI 'portmap' plugin, used to setup HostPorts for CNI, inserts rules at the front of the iptables nat chains; which take precedence over the KUBE- SERVICES chain. Because of this, the HostPort/portmap rule could match incoming traffic even if there were better fitting, more specific service definition rules like NodePorts later in the chain. The issue is fixed in CNI 0.7.5 and Kubernetes 1.11.9, 1.12.7, 1.13.5, and 1.14.0.