{
  "affected": [
    {
      "package": {
        "ecosystem": "Maven",
        "name": "org.opensearch.plugin:opensearch-security"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.18.0"
            },
            {
              "fixed": "2.19.4.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Maven",
        "name": "org.opensearch.plugin:opensearch-security"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.0.0"
            },
            {
              "fixed": "3.3.0.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [],
  "database_specific": {
    "cwe_ids": [
      "CWE-295"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-07T00:09:18Z",
    "nvd_published_at": null,
    "severity": "LOW"
  },
  "details": "### Description\n\nA regression was introduced in OpenSearch 2.18.0 that caused the `plugins.security.ssl.transport.enforce_hostname_verification` setting to be ineffective. When this setting was enabled, OpenSearch did not verify that the hostname in a connecting node\u0027s TLS certificate matched the hostname of the connection. This could allow a node with a valid certificate (signed by the cluster\u0027s trusted CA) but an incorrect hostname SAN to join the cluster.\n\n### Impact\n\nClusters running affected versions with hostname verification enabled did not receive the expected protection from this setting. A node presenting a certificate signed by the cluster\u0027s trusted CA could join the cluster regardless of whether its hostname SAN matched. This regression does not affect certificate validation itself \u2014 only the additional hostname verification check.\n\n### Patches\n\nThis issue is fixed in OpenSearch 2.19.4 and 3.3.0.\n\n### Workarounds\n\nUse more restrictive values for `plugins.security.nodes_dn` to limit which certificates are accepted for node-to-node communication.",
  "id": "GHSA-x5hg-x4gv-j98m",
  "modified": "2026-05-07T00:09:18Z",
  "published": "2026-05-07T00:09:18Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/opensearch-project/security/security/advisories/GHSA-x5hg-x4gv-j98m"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/opensearch-project/security"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "OpenSearch has ineffective TLS certificate hostname verification"
}