A third issue was discovered with the Kubernetes kubectl cp command that could enable a directory traversal such that a malicious container could replace or create files on a user’s workstation. The vulnerability is a client-side defect and requires user interaction to be exploited.

This vulnerability allows a malicious container to cause a file to be created or replaced on the client computer when the client uses the kubectl cp operation. The vulnerability is a client-side defect and requires user interaction to be exploited.

Upstream Issue:

https://github.com/kubernetes/kubernetes/issues/80984

External References:

https://groups.google.com/forum/#!topic/kubernetes-security-discuss/Vf31dXp0EJc

In all Kubernetes versions prior to v1.10.11, v1.11.5, and v1.12.3, incorrect handling of error responses to proxied upgrade requests in the kube-apiserver allowed specially crafted requests to establish a connection through the Kubernetes API server to backend servers, then send arbitrary requests over the same connection directly to the backend, authenticated with the Kubernetes API server's TLS credentials used to establish the backend connection.