Skipper is an HTTP router and reverse proxy for service composition. Prior to version 0.24.0, when running Skipper as an Ingress controller, users with permissions to create an Ingress and a Service of type ExternalName can create routes that enable them to use Skipper's network access to reach internal services. Version 0.24.0 disables Kubernetes ExternalName by default. As a workaround, developers can allow list targets of an ExternalName and allow list via regular expressions.

Skipper Ingress Controller Allows Unauthorized Access to Internal Services via ExternalName