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Capsule Namespace Hijacking via subresource

Type: advisorySources: OSV

Capsule is a multi-tenancy and policy-based framework for Kubernetes. To defend against namespace hijacking achieved through update/patch operations on namespaces, Capsule uses a webhook to validate update requests targeting namespaces. However, in Kubernetes, the namespace/finalize and namespace/status subresource APIs can also modify various fields of a namespace, including the metadata field. Prior to version 0.13.0, the webhook does not define interception rules for these subresources. As a result, if a tenant administrator has permission to modify namespace/status or namespace/finalize, they can successfully perform namespace hijacking. Version 0.13.0 fixes the issue. Another mitigation is to add two subresources (namespaces and snamespaces/status with namespace/finalize within it) to the resources list in the ValidatingWebhookConfiguration rules.

Products
Not specified
Affected versions
Not specified
Fixed versions
Not specified
CVEs
CVE-2026-30963
Confirmed fixed CVEs
Not specified
Updated in this feed
2 Nov 2026, 22:22 UTC · Revision 1

Source evidence

Capsule Namespace Hijacking via subresource

core-osv · Original source

Published 1 Jun 2026, 18:00 UTC

Capsule is a multi-tenancy and policy-based framework for Kubernetes. To defend against namespace hijacking achieved through update/patch operations on namespaces, Capsule uses a webhook to validate update requests targeting namespaces. However, in Kubernetes, the namespace/finalize and namespace/status subresource APIs can also modify various fields of a namespace, including the metadata field. Prior to version 0.13.0, the webhook does not define interception rules for these subresources. As a result, if a tenant administrator has permission to modify namespace/status or namespace/finalize, they can successfully perform namespace hijacking. Version 0.13.0 fixes the issue. Another mitigation is to add two subresources (namespaces and snamespaces/status with namespace/finalize within it) to the resources list in the ValidatingWebhookConfiguration rules.

osv:CVE-2026-30963
Complete source record
{
  "id": "1a6750ed84c9c7894f00ae30ad82aa17b476c6915a037d3e35d150e7bb94edaa",
  "url": "https://osv.dev/vulnerability/CVE-2026-30963",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Capsule Namespace Hijacking via subresource",
    "summary": "Capsule is a multi-tenancy and policy-based framework for Kubernetes. To defend against namespace hijacking achieved through update/patch operations on namespaces, Capsule uses a webhook to validate update requests targeting namespaces. However, in Kubernetes, the namespace/finalize and namespace/status subresource APIs can also modify various fields of a namespace, including the metadata field. Prior to version 0.13.0, the webhook does not define interception rules for these subresources. As a result, if a tenant administrator has permission to modify namespace/status or namespace/finalize, they can successfully perform namespace hijacking. Version 0.13.0 fixes the issue. Another mitigation is to add two subresources (namespaces and snamespaces/status with namespace/finalize within it) to the resources list in the ValidatingWebhookConfiguration rules.",
    "evidence": "osv:CVE-2026-30963",
    "products": [],
    "severity": "low",
    "structured": {
      "id": "CVE-2026-30963",
      "aliases": [
        "CVE-2026-30963",
        "GHSA-2ww6-hf35-mfjm",
        "GO-2026-5043"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:L/I:L/A:L"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/projectcapsule/capsule",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "c6e109ca46ed7de3a0f371df75e8abc993413a64"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "0.13.0"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "fixed": "c6e109ca46ed7de3a0f371df75e8abc993413a64"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "v0.13.0"
                  },
                  {
                    "cpe": "cpe:2.3:a:projectcapsule:capsule:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "0.13.0"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v0.11.2",
            "v0.12.4",
            "v0.12.3",
            "v0.12.2",
            "v0.12.1",
            "v0.12.0",
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            "helm-v0.6.0",
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            "helm-v0.5.2",
            "helm-v0.5.1",
            "helm-v0.4.7",
            "v0.4.0",
            "v0.4.0-rc.3",
            "helm-v0.5.0",
            "v0.4.0-rc.2",
            "v0.4.0-rc.1",
            "helm-v0.4.8",
            "helm-v0.4.6",
            "v0.3.3",
            "helm-v0.4.4",
            "v0.3.2",
            "helm-v0.4.3",
            "helm-v0.4.2",
            "v0.3.1",
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            "v0.1.2",
            "helm-v0.1.11",
            "helm-v0.1.10",
            "v0.1.2-rc1",
            "v0.1.2-rc0",
            "helm-v0.1.8",
            "helm-v0.1.7",
            "helm-v0.1.6",
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            "helm-v0.1.4",
            "v0.1.1-rc1",
            "helm-v0.1.3",
            "helm-v0.1.2",
            "helm-v0.1.1",
            "v0.1.1-rc0",
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            "helm-v0.1.0",
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            "v0.1.0-rc5",
            "v0.1.0-rc4",
            "v0.1.0-rc3",
            "v0.1.0-rc2",
            "v0.1.0-rc1",
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            "v0.0.5-rc2",
            "v0.0.5-rc1",
            "v0.0.4",
            "v0.0.3",
            "v0.0.2",
            "0.2.0-rc1",
            "v0.0.1",
            "0.0.1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-30963.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:23.916032625Z",
      "provider": "osv",
      "references": [
        "https://github.com/projectcapsule/capsule/releases/tag/v0.13.0",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/30xxx/CVE-2026-30963.json",
        "https://github.com/projectcapsule/capsule/security/advisories/GHSA-2ww6-hf35-mfjm",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-30963"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-20"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/30xxx/CVE-2026-30963.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-30963",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 490525,
  "published_at": "2026-06-01T18:00:43.797+00:00"
}