{"id":"GHSA-jr6p-8pjj-mfx6","summary":"Capsule has an incomplete fix of CVE-2026-22872: TenantResource RawItems and Generators still allow cluster-scoped resource creation (cross-tenant privilege escalation)","details":"### Summary\nCVE-2026-22872 (GHSA-qjjm-7j9w-pw72) reported that a Tenant Owner could create cluster-scoped resources\n(e.g. `ClusterRole`, `ValidatingWebhookConfiguration`) through a `TenantResource`, because the controller\napplies them with its cluster-admin ServiceAccount and `SetNamespace` is ineffective for cluster-scoped\nkinds. The v0.13.0 fix added a cluster-scope rejection guard, but **only on the NamespacedItems selection\npath** (`ResourceReference.LoadResources` -\u003e `IsNamespacedGVK`, error `\"cluster-scoped kind ... is not\nallowed\"`). The **RawItems create path — the exact vector the original advisory named — and the Generators\npath were not given this guard.** The vulnerability therefore persists in all releases **v0.13.0 through\nv0.13.7** and on trunk HEAD (`8d89d6865d`).\n\n### Details\nTenantResource reconcile flow:\n- `internal/controllers/resources/namespaced.go` `reconcile()` obtains the apply client via `loadClient()`;\n  by default (impersonation off, no `Spec.ServiceAccount`) this is the manager client whose SA is bound to\n  cluster-admin (`charts/capsule/templates/rbac.yaml:488-501`, `{fullname}-manager-rolebinding` -\u003e\n  roleRef cluster-admin).\n- `Collector.Collect()` (`collect.go`) processes `spec.RawItems` via `handleRawItem` and `spec.Generators`\n  via `handleGeneratorItem`.\n\n`handleRawItem` (`collect.go:406-425`, trunk HEAD — byte-identical to v0.13.0):\n```go\ntmplString := tpl.FastTemplate(string(item.Raw), opts.Iterator.FastContext)\nobj := &unstructured.Unstructured{}\nunstructured.UnstructuredJSONScheme.Decode([]byte(tmplString), nil, obj)\nif ns != nil { obj.SetNamespace(ns.Name) }   // ONLY mitigation\nreturn obj, nil                                // NO IsNamespacedGVK / allowClusterScoped guard\n```\n`handleGeneratorItem` (`collect.go:382-404`) is the same: it only `SetNamespace`s on rendered objects.\n\nThe accumulated objects flow to `pkg/api/processor/processor_func.go` `Reconcile()` -\u003e `Apply()` -\u003e\n`clt.PatchApply(ctx, c, obj, ...)` (line 167/378) with **no scope check at any point**.\n\nBy contrast, `CollectNamespacedItems` (`collect.go:308`) calls `item.LoadResources(..., allowClusterScoped=false)`,\nand `pkg/template/reference.go:105-107` enforces:\n```go\nif !allowClusterScoped && !isNamespaced {\n    return nil, fmt.Errorf(\"cluster-scoped kind %s/%s is not allowed\", ...)\n}\n```\nSo the guard the fix added is real, but it sits on a different (selection) path than the one the CVE\ndescribed (RawItems create path). For cluster-scoped kinds, `SetNamespace` is ignored by the Kubernetes API\nserver, so the object is created cluster-wide by the cluster-admin client.\n\n**Parent-fix diff confirmation:** in v0.12.4 the RawItems handler in `processor.go` was the vulnerable code\n(`obj.SetNamespace(ns.Name)` then `createOrUpdate` via `r.client`). v0.13.0 refactored this into\n`collect.go` `handleRawItem` but left it without the new guard.\n\n### Proof of Concept\nA self-contained in-process Go test (`incompletefix_poc_test.go`), run against trunk HEAD with go1.26.4,\nproves the asymmetry:\n- `TestRawItemPath_NoClusterScopeGuard`: feeds a `ClusterRole` rawItem to `handleRawItem` -\u003e object returned\n  unchanged, no rejection (PASS).\n- `TestNamespacedItemsPath_HasClusterScopeGuard`: feeds the same `ClusterRole` kind to\n  `LoadResources(allowClusterScoped=false)` -\u003e rejected with\n  `\"cluster-scoped kind rbac.authorization.k8s.io/v1/ClusterRole is not allowed\"` (PASS).\n\n```\nVULNERABLE: RawItems path accepted cluster-scoped rbac.authorization.k8s.io/v1/ClusterRole;\n            metadata.namespace=\"tenant-ns\" (ignored by API server for cluster-scoped kinds)\nGUARDED:    NamespacedItems path correctly rejected cluster-scoped kind:\n            cluster-scoped kind rbac.authorization.k8s.io/v1/ClusterRole is not allowed\n```\n\nEnd-to-end (cluster) reproduction:\n1. Deploy capsule (default Helm) with `rbac.resources.create=true` (the opt-in that exposes TenantResources\n   to tenant owners; the configuration the original CVE applies to).\n2. As a Tenant Owner, create in a tenant namespace:\n   ```yaml\n   apiVersion: capsule.clastix.io/v1beta2\n   kind: TenantResource\n   metadata: {name: pwn, namespace: \u003ctenant-ns\u003e}\n   spec:\n     resources:\n       - namespaceSelector: {matchLabels: {capsule.clastix.io/tenant: \u003ctenant\u003e}}\n         rawItems:\n           - apiVersion: rbac.authorization.k8s.io/v1\n             kind: ClusterRole\n             metadata: {name: tenant-escalation}\n             rules: [{apiGroups: [\"*\"], resources: [\"*\"], verbs: [\"*\"]}]\n   ```\n3. Observe the cluster-scoped ClusterRole `tenant-escalation` is created by the cluster-admin controller,\n   despite the tenant owner lacking cluster RBAC to create it. Swap in `ValidatingWebhookConfiguration`\n   to intercept/exfiltrate cluster-wide Secrets.\n\n### Impact\nA Tenant Owner (namespace-scoped) escalates to cluster-admin-equivalent privileges and can compromise all\ntenants and the cluster control plane. Identical impact to CVE-2026-22872; the v0.13.0 remediation does not\nclose the RawItems/Generators vector.\n\n### Remediation\nApply the same `IsNamespacedGVK` / `allowClusterScoped` rejection inside `handleRawItem` and\n`handleGeneratorItem` — or centrally in `Collector.AddToAccumulation` / `processor.Apply` — so the create\npath enforces the same cluster-scope policy as the selection path. (`GlobalTenantResource` shares the path\nbut is not a privesc — cluster-admin-only to create.)","aliases":["CVE-2026-65835","GO-2026-6157"],"modified":"2026-08-18T15:10:45.661105639Z","published":"2026-07-31T16:53:42Z","database_specific":{"github_reviewed":true,"github_reviewed_at":"2026-07-31T16:53:42Z","nvd_published_at":"2026-07-30T20:18:13Z","cwe_ids":["CWE-269","CWE-863"],"severity":"MODERATE"},"references":[{"type":"WEB","url":"https://github.com/projectcapsule/capsule/security/advisories/GHSA-jr6p-8pjj-mfx6"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-65835"},{"type":"PACKAGE","url":"https://github.com/projectcapsule/capsule"},{"type":"WEB","url":"https://github.com/projectcapsule/capsule/releases/tag/v0.13.8"}],"affected":[{"package":{"name":"github.com/projectcapsule/capsule","ecosystem":"Go","purl":"pkg:golang/github.com/projectcapsule/capsule"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0.13.0"},{"fixed":"0.13.8"}]}],"database_specific":{"last_known_affected_version_range":"\u003c= 0.13.7","source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-jr6p-8pjj-mfx6/GHSA-jr6p-8pjj-mfx6.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:L"}]}