CKAN is vulnerable to session secret shared across instances using Docker images

CKAN is an open-source DMS (data management system) for powering data hubs and data portals. When creating a new container based on one of the Docker images listed below, the same secret key was being used by default. If the users didn't set a custom value via environment variables in the .env file, that key was shared across different CKAN instances, making it easy to forge authentication requests. Users overriding the default secret key in their own .env file are not affected by this issue. Note that the legacy images (ckan/ckan) located in the main CKAN repo are not affected by this issue. The affected images are ckan/ckan-docker, (ckan/ckan-base images), okfn/docker-ckan (openknowledge/ckan-base and openknowledge/ckan-dev images) keitaroinc/docker-ckan (keitaro/ckan images).