Security advisory

{
  "id": "f0732427a641a86f2e40d0abea5660db63c843c2afd05251fc2d1eee418d0c59",
  "url": "https://osv.dev/vulnerability/CVE-2021-40524",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2021-40524",
    "summary": "In Pure-FTPd before 1.0.50, an incorrect max_filesize quota mechanism in the server allows attackers to upload files of unbounded size, which may lead to denial of service or a server hang. This occurs because a certain greater-than-zero test does not anticipate an initial -1 value. (Versions 1.0.23 through 1.0.49 are affected.)",
    "evidence": "osv:CVE-2021-40524",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2021-40524",
      "aliases": [
        "CVE-2021-40524"
      ],
      "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/jedisct1/pure-ftpd",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "868f0e2277e3f5890ca08c84d41de8065a7d8bc3"
                },
                {
                  "fixed": "37ad222868e52271905b94afea4fc780d83294b4"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:pureftpd:pure-ftpd:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "1.0.23"
                      },
                      {
                        "fixed": "1.0.50"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "range": [
                      {
                        "fixed": "37ad222868e52271905b94afea4fc780d83294b4"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "versions": [
            "1.0.49",
            "1.0.48",
            "1.0.45",
            "1.0.44",
            "1.0.43",
            "1.0.41",
            "1.0.40",
            "1.0.39",
            "1.0.38",
            "1.0.37",
            "1.0.36",
            "1.0.35",
            "1.0.34",
            "1.0.33"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-40524.json",
            "vanir_signatures": [
              {
                "id": "CVE-2021-40524-00e4d04c",
                "digest": {
                  "threshold": 0.9,
                  "line_hashes": [
                    "62861421324718626283205813091113225033",
                    "276556215880805753523756337752274567287",
                    "139825961526930270406704652117385392827"
                  ]
                },
                "source": "https://github.com/jedisct1/pure-ftpd/commit/868f0e2277e3f5890ca08c84d41de8065a7d8bc3",
                "target": {
                  "file": "src/simpleconf_ftpd.h"
                },
                "deprecated": false,
                "signature_type": "Line",
                "signature_version": "v1"
              },
              {
                "id": "CVE-2021-40524-178db787",
                "digest": {
                  "threshold": 0.9,
                  "line_hashes": [
                    "143088216645301880473965997968294163065",
                    "268607288337989793077162423436249802443",
                    "280366719401112403696117270706084821257",
                    "25497428101258363206954973861780601325",
                    "122625483517188019176324232254541051564"
                  ]
                },
                "source": "https://github.com/jedisct1/pure-ftpd/commit/37ad222868e52271905b94afea4fc780d83294b4",
                "target": {
                  "file": "src/ftpd.c"
                },
                "deprecated": false,
                "signature_type": "Line",
                "signature_version": "v1"
              },
              {
                "id": "CVE-2021-40524-1865d9b9",
                "digest": {
                  "length": 5664,
                  "function_hash": "310052781692296683813829170466513134176"
                },
                "source": "https://github.com/jedisct1/pure-ftpd/commit/37ad222868e52271905b94afea4fc780d83294b4",
                "target": {
                  "file": "src/ftpd.c",
                  "function": "dostor"
                },
                "deprecated": false,
                "signature_type": "Function",
                "signature_version": "v1"
              }
            ],
            "vanir_signatures_modified": "2026-10-20T14:08:49Z"
          }
        }
      ],
      "modified": "2026-10-20T14:08:49.205015610Z",
      "provider": "osv",
      "references": [
        "https://lists.debian.org/debian-lts-announce/2025/11/msg00003.html",
        "https://github.com/jedisct1/pure-ftpd/commit/37ad222868e52271905b94afea4fc780d83294b4",
        "https://github.com/jedisct1/pure-ftpd/compare/1.0.49...1.0.50",
        "https://github.com/jedisct1/pure-ftpd/pull/158"
      ],
      "provider_metadata": {}
    },
    "related_cves": [
      {
        "value": "CVE-2021-40524",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 388578,
  "published_at": "2021-09-05T19:15:15.08+00:00"
}