Security advisory

{
  "id": "4a93ab772fd041bd920e0889b6b4e3b1d0d626c1c21254e917f75972d8d09d69",
  "url": "https://osv.dev/vulnerability/CVE-2021-42343",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2021-42343",
    "summary": "An issue was discovered in the Dask distributed package before 2021.10.0 for Python. Single machine Dask clusters started with dask.distributed.LocalCluster or dask.distributed.Client (which defaults to using LocalCluster) would mistakenly configure their respective Dask workers to listen on external interfaces (typically with a randomly selected high port) rather than only on localhost. A Dask cluster created using this method (when running on a machine that has an applicable port exposed) could be used by a sophisticated attacker to achieve remote code execution.",
    "evidence": "osv:CVE-2021-42343",
    "products": [],
    "severity": "critical",
    "structured": {
      "id": "CVE-2021-42343",
      "aliases": [
        "CVE-2021-42343",
        "GHSA-hwqr-f3v9-hwxr",
        "GHSA-j8fq-86c5-5v2r",
        "PYSEC-2021-387",
        "PYSEC-2021-871"
      ],
      "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/dask/dask",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "97494ff0d5d935e534871c9cf0d5b642fd74edb7"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:anaconda:dask:*:*:*:*:*:python:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "2021.10.0"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "2021.09.1",
            "2021.09.0",
            "2021.08.1",
            "2021.08.0",
            "2021.07.2",
            "2021.07.1",
            "2021.07.0",
            "2021.06.2",
            "2021.06.1",
            "2021.06.0",
            "2021.05.1",
            "2021.05.0",
            "2021.04.1",
            "2021.04.0",
            "2021.03.1",
            "2021.03.0",
            "2021.02.0",
            "2021.01.1",
            "2021.01.0",
            "2020.12.0",
            "2.30.0",
            "2.29.0",
            "2.28.0",
            "2.27.0",
            "2.26.0",
            "2.25.0",
            "2.24.0",
            "2.23.0",
            "2.22.0",
            "2.21.0",
            "2.20.0",
            "2.19.0",
            "2.18.1",
            "2.18.0",
            "2.17.2",
            "2.17.1",
            "2.17.0",
            "2.16.0",
            "2.15.0",
            "2.14.0",
            "2.13.0",
            "2.12.0",
            "2.11.0",
            "2.10.1",
            "2.10.0",
            "2.9.2",
            "2.9.1",
            "2.9.0",
            "2.8.1",
            "2.8.0",
            "2.7.0",
            "2.6.0",
            "2.5.2",
            "2.5.0",
            "2.4.0",
            "2.3.0",
            "2.2.0",
            "2.1.0",
            "2.0.0",
            "1.2.2",
            "1.2.1",
            "1.2.0",
            "1.1.5",
            "1.1.4",
            "1.1.3",
            "1.1.2",
            "1.1.1",
            "1.1.0",
            "1.0.0",
            "1.0.0.rc1",
            "0.20.2",
            "0.20.1",
            "0.20.0",
            "0.19.4",
            "0.19.3",
            "0.19.2",
            "0.19.1",
            "0.19.0",
            "0.18.2",
            "0.18.1",
            "0.18.0",
            "0.17.4",
            "0.17.3",
            "0.17.2",
            "0.17.1",
            "0.17.0",
            "0.16.1",
            "0.16.0",
            "0.15.4",
            "0.15.3",
            "0.15.2",
            "0.15.1",
            "0.15.0",
            "0.14.3",
            "0.14.2",
            "0.14.1",
            "0.14.0",
            "0.13.0",
            "0.12.0",
            "0.11.1",
            "0.11.0",
            "0.10.2",
            "0.10.1",
            "0.10.0",
            "0.9.0",
            "0.8.2",
            "0.8.1",
            "0.8.0",
            "0.7.6",
            "0.7.5",
            "0.7.4",
            "0.7.3",
            "0.7.2",
            "0.7.1",
            "0.7.0",
            "list",
            "0.6.1",
            "0.6.0",
            "0.5.0",
            "0.4.0",
            "0.3.0",
            "0.2.6",
            "0.2.5",
            "0.2.3",
            "0.2.2",
            "0.2.1",
            "0.2.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-42343.json"
          }
        }
      ],
      "modified": "2026-10-20T10:55:00.825813172Z",
      "provider": "osv",
      "references": [
        "https://docs.dask.org/en/latest/changelog.html",
        "https://github.com/dask/dask/tags",
        "https://github.com/dask/distributed/security/advisories/GHSA-hwqr-f3v9-hwxr"
      ],
      "provider_metadata": {}
    },
    "related_cves": [
      {
        "value": "CVE-2021-42343",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 386679,
  "published_at": "2021-10-26T11:15:07.8+00:00"
}