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Medium

Bypass of namespace restrictions in CiliumNetworkPolicy

Type: advisorySources: OSV

Cilium is a networking, observability, and security solution with an eBPF-based dataplane. An attacker with the ability to create or modify CiliumNetworkPolicy objects in a particular namespace is able to affect traffic on an entire Cilium cluster, potentially bypassing policy enforcement in other namespaces. By using a crafted `endpointSelector` that uses the `DoesNotExist` operator on the `reserved:init` label, the attacker can create policies that bypass namespace restrictions and affect the entire Cilium cluster. This includes potentially allowing or denying all traffic. This attack requires API server access, as described in the Kubernetes API Server Attacker section of the Cilium Threat Model. This issue has been resolved in Cilium versions 1.14.2, 1.13.7, and 1.12.14. As a workaround an admission webhook can be used to prevent the use of `endpointSelectors` that use the `DoesNotExist` operator on the `reserved:init` label in CiliumNetworkPolicies.

Products
Not specified
Affected versions
Not specified
Fixed versions
Not specified
CVEs
CVE-2023-41333
Confirmed fixed CVEs
Not specified
Updated in this feed
7 Nov 2026, 14:55 UTC · Revision 1

Source evidence

Bypass of namespace restrictions in CiliumNetworkPolicy

core-osv · Original source

Published 26 Sept 2023, 20:19 UTC

Cilium is a networking, observability, and security solution with an eBPF-based dataplane. An attacker with the ability to create or modify CiliumNetworkPolicy objects in a particular namespace is able to affect traffic on an entire Cilium cluster, potentially bypassing policy enforcement in other namespaces. By using a crafted `endpointSelector` that uses the `DoesNotExist` operator on the `reserved:init` label, the attacker can create policies that bypass namespace restrictions and affect the entire Cilium cluster. This includes potentially allowing or denying all traffic. This attack requires API server access, as described in the Kubernetes API Server Attacker section of the Cilium Threat Model. This issue has been resolved in Cilium versions 1.14.2, 1.13.7, and 1.12.14. As a workaround an admission webhook can be used to prevent the use of `endpointSelectors` that use the `DoesNotExist` operator on the `reserved:init` label in CiliumNetworkPolicies.

osv:CVE-2023-41333
Complete source record
{
  "id": "d0371667c0f602f2b06483b1db340522ac2d07faf17e8f26d7a193649fc44382",
  "url": "https://osv.dev/vulnerability/CVE-2023-41333",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Bypass of namespace restrictions in CiliumNetworkPolicy",
    "summary": "Cilium is a networking, observability, and security solution with an eBPF-based dataplane. An attacker with the ability to create or modify CiliumNetworkPolicy objects in a particular namespace is able to affect traffic on an entire Cilium cluster, potentially bypassing policy enforcement in other namespaces. By using a crafted `endpointSelector` that uses the `DoesNotExist` operator on the `reserved:init` label, the attacker can create policies that bypass namespace restrictions and affect the entire Cilium cluster. This includes potentially allowing or denying all traffic. This attack requires API server access, as described in the Kubernetes API Server Attacker section of the Cilium Threat Model. This issue has been resolved in Cilium versions 1.14.2, 1.13.7, and 1.12.14. As a workaround an admission webhook can be used to prevent the use of `endpointSelectors` that use the `DoesNotExist` operator on the `reserved:init` label in CiliumNetworkPolicies.",
    "evidence": "osv:CVE-2023-41333",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2023-41333",
      "aliases": [
        "BIT-cilium-2023-41333",
        "BIT-cilium-operator-2023-41333",
        "BIT-cilium-proxy-2023-41333",
        "BIT-hubble-2023-41333",
        "BIT-hubble-relay-2023-41333",
        "BIT-hubble-ui-2023-41333",
        "BIT-hubble-ui-backend-2023-41333",
        "CVE-2023-41333",
        "GHSA-4xp2-w642-7mcx",
        "GO-2023-2080"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:C/C:L/I:N/A:H"
        }
      ],
      "affected": [
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              "type": "GIT",
              "events": [
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          "versions": [
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          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2023-41333.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:51.253630673Z",
      "provider": "osv",
      "references": [
        "https://docs.cilium.io/en/stable/security/threat-model/#kubernetes-api-server-attacker",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/41xxx/CVE-2023-41333.json",
        "https://github.com/cilium/cilium/security/advisories/GHSA-4xp2-w642-7mcx",
        "https://nvd.nist.gov/vuln/detail/CVE-2023-41333",
        "https://github.com/cilium/cilium/pull/28007"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-306"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/41xxx/CVE-2023-41333.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2023-41333",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 519692,
  "published_at": "2023-09-26T20:19:34.512+00:00"
}