Hello Kubernetes Community,
A security issue was discovered in Kubernetes where users may be able to launch containers that bypass the mountable secrets policy enforced by the ServiceAccount admission plugin when using ephemeral containers. The policy ensures pods running with a service account may only reference secrets specified in the service account’s secrets field. Kubernetes clusters are only affected if the ServiceAccount admission plugin and the kubernetes.io/enforce-mountable-secrets
annotation are used together with ephemeral containers.
This issue has been rated Medium
), and assigned CVE-2023-2728
Am I vulnerable?
Clusters are impacted by this vulnerability if all of the following are true:
- kube-apiserver v1.27.0 - v1.27.2
- kube-apiserver v1.26.0 - v1.26.5
- kube-apiserver v1.25.0 - v1.25.10
- kube-apiserver <= v1.24.14
How do I mitigate this vulnerability?
This issue can be mitigated by applying the patch provided for the kube-apiserver component. The patch prevents ephemeral containers from bypassing the mountable secrets policy enforced by the ServiceAccount admission plugin.
- kube-apiserver v1.27.3
- kube-apiserver v1.26.6
- kube-apiserver v1.25.11
- kube-apiserver v1.24.15
These releases have been published today, June 14th, 2023.
Pod update requests using an ephemeral container that exploits this vulnerability with unintended secret will be captured in API audit logs. You can also use kubectl get pods to find active pods with ephemeral containers running with a secret that is not referenced by the service account in your cluster.
Rita Zhang on behalf of the Kubernetes Security Response Committee