Strimzi: Privilege escalation via Console custom resource image injection (CVE-2026-105312)

CVE-2026-105312 is a security vulnerability in the Strimzi Kubernetes operator that allows for cross-tenant privilege escalation. A tenant with 'create' permissions on Console custom resources can manipulate the 'spec.containers.api.spec.image' field, forcing the operator to deploy an arbitrary container image under its control. The operator subsequently deploys this image into a pod associated with a ServiceAccount that has high-privilege access, including cluster-wide get, list, and watch permissions on all Strimzi Custom Resource Definitions (CRDs) such as KafkaUsers, as well as patch permissions on Kafkas and KafkaRebalances. An attacker exploiting this can read the projected ServiceAccount token from within the container to gain unauthorized control-plane access, effectively bypassing tenant isolation to read or modify Kafka resources across the cluster.

Attack Chain

1. Attacker identifies a Kubernetes namespace where they possess 'create' permissions on Console custom resources.
2. Attacker crafts a malicious Console custom resource definition containing a crafted 'spec.containers.api.spec.image' value pointing to an attacker-controlled container image.
3. Attacker submits the malicious Console custom resource to the Kubernetes API server.
4. The Strimzi operator reconciles the malicious resource and pulls the attacker-controlled image.
5. The Strimzi operator deploys the malicious image into a pod context managed by the operator.
6. The pod initializes with a ServiceAccount bound via ClusterRoleBinding to a high-privilege Strimzi ClusterRole.
7. Attacker executes code within the running container to access the projected ServiceAccount token located in the filesystem.
8. Attacker uses the stolen ServiceAccount token to perform unauthorized cross-tenant operations, such as modifying KafkaUsers or Kafka resources.

Impact

Successful exploitation allows a low-privileged tenant to gain elevated, cluster-wide control over Strimzi Kafka deployments. This results in unauthorized access to sensitive Kafka data, the ability to modify or delete Kafka users and cluster configurations, and potential disruption to cross-tenant messaging services.

Recommendation

1. Audit Kubernetes RBAC policies to restrict 'create' permissions on Console custom resources to trusted administrative principals only.
2. Implement admission controllers to validate image registry sources for pods created by operators, ensuring only authorized container images are deployed.
3. Review existing ClusterRoleBindings associated with Strimzi ServiceAccounts to ensure they adhere to the principle of least privilege.
4. Upgrade to the latest patched version of the Strimzi operator as provided by the vendor.