Security advisory

{
  "id": "c2b4134610ade6298574db1679cde92870aaab7928cd34c879f4e2d3fbd75e70",
  "url": "https://osv.dev/vulnerability/CVE-2021-3828",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2021-3828",
    "summary": "nltk is vulnerable to Inefficient Regular Expression Complexity",
    "evidence": "osv:CVE-2021-3828",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2021-3828",
      "aliases": [
        "CVE-2021-3828",
        "GHSA-2ww3-fxvq-293j",
        "PYSEC-2021-356"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/nltk/nltk",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "last_affected": "a1034bbec30c2ec5765c9497cb8167b26a3c5d0e"
                },
                {
                  "fixed": "277711ab1dec729e626b27aab6fa35ea5efbd7e6"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:nltk:nltk:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "last_affected": "3.6.3"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "range": [
                      {
                        "fixed": "277711ab1dec729e626b27aab6fa35ea5efbd7e6"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "versions": [
            "3.6.3",
            "3.6.2",
            "3.6.1",
            "3.6",
            "3.5",
            "3.5b1",
            "3.4.4",
            "3.4.3",
            "3.4.1",
            "3.4",
            "3.3",
            "3.2.5",
            "3.2.4",
            "3.2.3",
            "3.2.2",
            "3.2.1",
            "3.2",
            "3.1",
            "3.0.5",
            "3.0.4",
            "3.0.3",
            "3.0.2",
            "3.0.0b1",
            "3.0a4",
            "2.0.1rc4",
            "2.0.1rc3",
            "2.0.1rc2",
            "2.0.1rc1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-3828.json"
          }
        }
      ],
      "modified": "2026-10-20T10:54:51.265657511Z",
      "provider": "osv",
      "references": [
        "https://github.com/nltk/nltk/commit/277711ab1dec729e626b27aab6fa35ea5efbd7e6",
        "https://huntr.dev/bounties/d19aed43-75bc-4a03-91a0-4d0bb516bc32"
      ],
      "provider_metadata": {}
    },
    "related_cves": [
      {
        "value": "CVE-2021-3828",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 386283,
  "published_at": "2021-09-27T13:15:07.993+00:00"
}