Security advisory

{
  "id": "23f1f57a3d172a06044b8bbc010a861c624fa1fd6ef43ce89546317ae1ee9be2",
  "url": "https://osv.dev/vulnerability/CVE-2021-23180",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2021-23180",
    "summary": "A flaw was found in htmldoc in v1.9.12 and before. Null pointer dereference in file_extension(),in file.c may lead to execute arbitrary code and denial of service.",
    "evidence": "osv:CVE-2021-23180",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2021-23180",
      "aliases": [
        "CVE-2021-23180"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/michaelrsweet/htmldoc",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "last_affected": "df5d3010151a506c5ca138548aac02b37fb421f9"
                },
                {
                  "fixed": "19c582fb32eac74b57e155cffbb529377a9e751a"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:htmldoc_project:htmldoc:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "last_affected": "1.9.12"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "range": [
                      {
                        "fixed": "19c582fb32eac74b57e155cffbb529377a9e751a"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v1.9.11",
            "v1.9.10",
            "v1.9.9",
            "v1.9.8",
            "v1.9.7",
            "v1.9.6",
            "v1.9.5",
            "v1.9.4",
            "v1.9.3",
            "v1.9.2",
            "v1.9.1",
            "v1.9",
            "v1.8.30"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-23180.json",
            "vanir_signatures": [
              {
                "id": "CVE-2021-23180-93d131e5",
                "digest": {
                  "length": 832,
                  "function_hash": "214173865665023147144296000261361719556"
                },
                "source": "https://github.com/michaelrsweet/htmldoc/commit/19c582fb32eac74b57e155cffbb529377a9e751a",
                "target": {
                  "file": "htmldoc/file.c",
                  "function": "file_extension"
                },
                "deprecated": false,
                "signature_type": "Function",
                "signature_version": "v1"
              },
              {
                "id": "CVE-2021-23180-9e7a8c11",
                "digest": {
                  "threshold": 0.9,
                  "line_hashes": [
                    "222690638848438741200169568887037404330",
                    "118963740648647026022596039506257666025",
                    "182008003180137975600728763971343228999",
                    "81244088281243808798326873331165377534",
                    "87047512033200192692469376183636880049",
                    "132354921858136572642188747086448041024",
                    "20442359897743404521499468429548051351",
                    "122088147027535953071607880319169453471"
                  ]
                },
                "source": "https://github.com/michaelrsweet/htmldoc/commit/19c582fb32eac74b57e155cffbb529377a9e751a",
                "target": {
                  "file": "htmldoc/file.c"
                },
                "deprecated": false,
                "signature_type": "Line",
                "signature_version": "v1"
              }
            ],
            "vanir_signatures_modified": "2026-10-20T14:18:22Z"
          }
        }
      ],
      "modified": "2026-10-20T14:18:22.869114193Z",
      "provider": "osv",
      "references": [
        "https://ubuntu.com/security/CVE-2021-23180",
        "https://github.com/michaelrsweet/htmldoc/issues/418",
        "https://bugzilla.redhat.com/show_bug.cgi?id=1967041",
        "https://github.com/michaelrsweet/htmldoc/commit/19c582fb32eac74b57e155cffbb529377a9e751a"
      ],
      "provider_metadata": {}
    },
    "related_cves": [
      {
        "value": "CVE-2021-23180",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 388793,
  "published_at": "2022-03-02T23:15:08.283+00:00"
}