Authorization Bypass Through User-Controlled Key in Elasticsearch Leading to Information Disclosure

{
  "id": "c3863dff778368978bdabd65f1e556ef2e9625d4b7286210de57eac4ed4467e2",
  "url": "https://osv.dev/vulnerability/BIT-elasticsearch-2026-103009",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Authorization Bypass Through User-Controlled Key in Elasticsearch Leading to Information Disclosure",
    "summary": "Authorization Bypass Through User-Controlled Key (CWE-639) in Elasticsearch can lead to Information Disclosure via a specially crafted cross-cluster search request that references an unauthorized shard identifier. Elasticsearch contains an authorization bypass weakness in its handling of cross-cluster search requests made through the Remote Cluster Security (RCS) 2.0 model. An authorization check validates a request against one identifying attribute of the target shard, while a separate, independently-supplied identifying attribute in the same request determines which shard is actually accessed. A holder of a cross-cluster API key authorized for one index can craft a request whose two identifying attributes refer to different indices, causing the request to be authorized against an index they can access while actually operating against a different, unauthorized index. This can expose that index's document contents, field mappings, and other metadata, and in limited cases allows modification of retention-lease state on the unauthorized index.",
    "evidence": "osv:BIT-elasticsearch-2026-103009",
    "products": [
      {
        "name": {
          "value": "elasticsearch",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "8.19.23",
            "evidence": "/affected/0/ranges"
          },
          {
            "value": "9.4.8",
            "evidence": "/affected/0/ranges"
          },
          {
            "value": "9.5.5",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "BIT-elasticsearch-2026-103009",
      "aliases": [
        "BIT-elasticsearch-2026-103009",
        "CVE-2026-103009"
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "8.13.0"
                },
                {
                  "fixed": "8.19.23"
                },
                {
                  "introduced": "9.0.0"
                },
                {
                  "fixed": "9.4.8"
                },
                {
                  "introduced": "9.5.0"
                },
                {
                  "fixed": "9.5.5"
                }
              ]
            }
          ],
          "package": {
            "name": "elasticsearch",
            "purl": "pkg:bitnami/elasticsearch",
            "ecosystem": "Bitnami"
          },
          "severity": [
            {
              "type": "CVSS_V3",
              "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N"
            }
          ],
          "database_specific": {
            "source": "https://github.com/bitnami/vulndb/tree/main/data/elasticsearch/BIT-elasticsearch-2026-103009.json"
          }
        }
      ],
      "modified": "2026-10-14T11:00:06.203229209Z",
      "provider": "osv",
      "references": [
        "https://discuss.elastic.co/t/elasticsearch-8-19-23-9-4-8-9-5-5-security-update-esa-2026-199/390874",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-103009"
      ],
      "provider_metadata": {
        "cpes": [
          "cpe:2.3:a:elastic:elasticsearch:*:*:*:*:*:*:*:*",
          "cpe:2.3:a:elastic:elasticsearch:*:*:*:*:*:maven:*:*"
        ],
        "severity": "High"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-103009",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/database_specific/severity"
  },
  "source_id": "core-osv",
  "document_id": 316154,
  "published_at": "2026-10-13T06:47:26.127+00:00"
}