In Rancher 2 through 2.2.3, Project owners can inject additional fluentd configuration to read files or execute arbitrary commands inside the fluentd container.

In Rancher 2.0.0 through 2.1.5, project members have continued access to create, update, read, and delete namespaces in a project after they have been removed from it.

An issue was discovered in Rancher 2 through 2.1.5. Any project member with access to the default namespace can mount the netes-default service account in a pod, and then use that pod to execute administrative privileged commands against the k8s cluster. This could be mitigated by isolating the default namespace in a separate project, where only cluster admins can be given permissions to access. As of 2018-12-20, this bug affected ALL clusters created or imported by Rancher.

Rancher Labs rancher server 1.2.0+ is vulnerable to authenticated users disabling access control via an API call. This is fixed in versions rancher/server:v1.2.4, rancher/server:v1.3.5, rancher/server:v1.4.3, and rancher/server:v1.5.3.