Unintended Proxy or Intermediary in Elastic Cloud on Kubernetes Leading to Cross-Namespace Secret Disclosure

The Elastic Cloud on Kubernetes (ECK) operator reads a list of secret references from an annotation on secrets it manages, and it accepts the namespace recorded in each reference without validating that the reference is authorized for the resource being reconciled. A user whose Kubernetes permissions are limited to their own namespace can write that annotation, trigger a reconcile, and cause the operator to use its cluster-wide secret permissions to copy the contents of a secret from any other namespace into a secret the user can read.