Security advisory

{
  "id": "d17d31cecb2ae6419a30e1bcfb063defb516fc4f1b453ce5d76cf6f0b9f49527",
  "url": "https://osv.dev/vulnerability/CVE-2021-31921",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2021-31921",
    "summary": "Istio before 1.8.6 and 1.9.x before 1.9.5 contains a remotely exploitable vulnerability where an external client can access unexpected services in the cluster, bypassing authorization checks, when a gateway is configured with AUTO_PASSTHROUGH routing configuration.",
    "evidence": "osv:CVE-2021-31921",
    "products": [],
    "severity": "critical",
    "structured": {
      "id": "CVE-2021-31921",
      "aliases": [
        "CVE-2021-31921"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/istio/istio",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "1aa9fc7a594d6ffc88ff8fd6cd416d8bafe4b214"
                },
                {
                  "introduced": "b63e1966c245924b10a0915a671a656540ed7a45"
                },
                {
                  "fixed": "67362755b7ca63ff1442d627a733627ed5c75df4"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:istio:istio:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "1.8.6"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "cpe": "cpe:2.3:a:istio:istio:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "1.9.0"
                      },
                      {
                        "fixed": "1.9.5"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "1.9.4",
            "1.9.2",
            "1.8.4",
            "1.9.1",
            "1.8.3",
            "1.9.0",
            "1.8.2",
            "1.8.1",
            "1.8.0-rc.1",
            "1.8.0",
            "1.8.0-rc.0",
            "1.8.0-alpha.2",
            "1.8.0-alpha.0",
            "1.7.0-alpha.0",
            "1.6.0-alpha.2",
            "1.6.0-alpha.1",
            "1.6.0-alpha.0",
            "1.5.0-beta.2",
            "1.5.0-beta.1",
            "1.5.0-alpha.0",
            "1.2.0-rc.3",
            "1.2.0-rc.0",
            "1.1.0-snapshot.2",
            "1.1.0.snapshot.1",
            "1.1.0.snapshot.0",
            "1.0.0-snapshot.0",
            "0.6.0",
            "0.5.0",
            "0.3.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-31921.json"
          }
        }
      ],
      "modified": "2026-10-24T10:30:17.479926864Z",
      "provider": "osv",
      "references": [
        "https://istio.io/latest/news/security/istio-security-2021-006/"
      ],
      "provider_metadata": {}
    },
    "related_cves": [
      {
        "value": "CVE-2021-31921",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 429575,
  "published_at": "2021-06-02T16:15:08.927+00:00"
}