Capsule

Capsule is a multi-tenancy and policy-based framework for Kubernetes. In Capsule v0.7.0 and earlier, the tenant-owner can patch any arbitrary namespace that has not been taken over by a tenant (i.e., namespaces without the ownerReference field), thereby gaining control of that namespace. Version 0.7.1 contains a patch.

Published: 2024-08-20T14:33:24.518Z
Updated: 2025-08-14T13:32:03.818Z

capsule-proxy is a reverse proxy for Capsule kubernetes multi-tenancy framework. A bug in the RoleBinding reflector used by `capsule-proxy` gives ServiceAccount tenant owners the right to list Namespaces of other tenants backed by the same owner kind and name. For example consider two tenants `solar` and `wind`. Tenant `solar`, owned by a ServiceAccount named `tenant-owner` in the Namespace `solar`. Tenant `wind`, owned by a ServiceAccount named `tenant-owner` in the Namespace `wind`. The Tenant owner `solar` would be able to list the namespaces of the Tenant `wind` and vice-versa, although this is not correct. The bug introduces an exfiltration vulnerability since allows the listing of Namespace resources of other Tenants, although just in some specific conditions: 1. `capsule-proxy` runs with the `--disable-caching=false` (default value: `false`) and 2. Tenant owners are ServiceAccount, with the same resource name, but in different Namespaces. This vulnerability doesn't allow any privilege escalation on the outer tenant Namespace-scoped resources, since the Kubernetes RBAC is enforcing this. This issue has been addressed in version 0.4.5. Users are advised to upgrade. There are no known workarounds for this vulnerability.

Published: 2023-11-06T18:34:13.555Z
Updated: 2024-08-02T20:37:40.135Z

Capsule is a multi-tenancy and policy-based framework for Kubernetes. Prior to version 0.1.3, a ServiceAccount deployed in a Tenant Namespace, when granted with `PATCH` capabilities on its own Namespace, is able to edit it and remove the Owner Reference, breaking the reconciliation of the Capsule Operator and removing all the enforcement like Pod Security annotations, Network Policies, Limit Range and Resource Quota items. An attacker could detach the Namespace from a Tenant that is forbidding starting privileged Pods using the Pod Security labels by removing the OwnerReference, removing the enforcement labels, and being able to start privileged containers that would be able to start a generic Kubernetes privilege escalation. Patches have been released for version 0.1.3. No known workarounds are available.

Published: 2022-12-02T18:22:21.817Z
Updated: 2025-04-23T16:32:56.226Z