Vulnerability-Lookup

FKIE_CVE-2021-40524

Vulnerability from fkie_nvd - Published: 2021-09-05 19:15 - Updated: 2026-06-17 04:07

Severity

7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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.)

References

URL	Tags
cve@mitre.org	https://github.com/jedisct1/pure-ftpd/commit/37ad222868e52271905b94afea4fc780d83294b4	Patch, Third Party Advisory
cve@mitre.org	https://github.com/jedisct1/pure-ftpd/compare/1.0.49...1.0.50	Patch, Third Party Advisory
cve@mitre.org	https://github.com/jedisct1/pure-ftpd/pull/158	Exploit, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108	https://github.com/jedisct1/pure-ftpd/commit/37ad222868e52271905b94afea4fc780d83294b4	Patch, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108	https://github.com/jedisct1/pure-ftpd/compare/1.0.49...1.0.50	Patch, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108	https://github.com/jedisct1/pure-ftpd/pull/158	Exploit, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108	https://lists.debian.org/debian-lts-announce/2025/11/msg00003.html

Impacted products

	Vendor	Product	Version
	pureftpd	pure-ftpd	*

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "n/a",
          "vendor": "n/a",
          "versions": [
            {
              "status": "affected",
              "version": "n/a"
            }
          ]
        }
      ],
      "source": "cve@mitre.org"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:pureftpd:pure-ftpd:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "1BB7E569-40DC-47B8-AD6A-4F3EF8C0D092",
              "versionEndExcluding": "1.0.50",
              "versionStartIncluding": "1.0.23",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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.)"
    },
    {
      "lang": "es",
      "value": "En Pure-FTPd antes de la versi\u00f3n 1.0.50, un mecanismo incorrecto de cuota max_filesize en el servidor permite a los atacantes subir archivos de tama\u00f1o no limitado, lo que puede llevar a la denegaci\u00f3n de servicio o a la ca\u00edda del servidor. Esto ocurre porque una determinada prueba mayor que cero no anticipa un valor inicial de -1. (Est\u00e1n afectadas las versiones 1.0.23 a 1.0.49)"
    }
  ],
  "id": "CVE-2021-40524",
  "lastModified": "2026-06-17T04:07:05.163",
  "metrics": {
    "cvssMetricV2": [
      {
        "acInsufInfo": false,
        "baseSeverity": "MEDIUM",
        "cvssData": {
          "accessComplexity": "LOW",
          "accessVector": "NETWORK",
          "authentication": "NONE",
          "availabilityImpact": "PARTIAL",
          "baseScore": 5.0,
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "vectorString": "AV:N/AC:L/Au:N/C:N/I:N/A:P",
          "version": "2.0"
        },
        "exploitabilityScore": 10.0,
        "impactScore": 2.9,
        "obtainAllPrivilege": false,
        "obtainOtherPrivilege": false,
        "obtainUserPrivilege": false,
        "source": "nvd@nist.gov",
        "type": "Primary",
        "userInteractionRequired": false
      }
    ],
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 7.5,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 3.6,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ]
  },
  "published": "2021-09-05T19:15:15.080",
  "references": [
    {
      "source": "cve@mitre.org",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "url": "https://github.com/jedisct1/pure-ftpd/commit/37ad222868e52271905b94afea4fc780d83294b4"
    },
    {
      "source": "cve@mitre.org",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "url": "https://github.com/jedisct1/pure-ftpd/compare/1.0.49...1.0.50"
    },
    {
      "source": "cve@mitre.org",
      "tags": [
        "Exploit",
        "Third Party Advisory"
      ],
      "url": "https://github.com/jedisct1/pure-ftpd/pull/158"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "url": "https://github.com/jedisct1/pure-ftpd/commit/37ad222868e52271905b94afea4fc780d83294b4"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "url": "https://github.com/jedisct1/pure-ftpd/compare/1.0.49...1.0.50"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Exploit",
        "Third Party Advisory"
      ],
      "url": "https://github.com/jedisct1/pure-ftpd/pull/158"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "url": "https://lists.debian.org/debian-lts-announce/2025/11/msg00003.html"
    }
  ],
  "sourceIdentifier": "cve@mitre.org",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-434"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}

CVE-2021-40524 (GCVE-0-2021-40524)

Vulnerability from cvelistv5 – Published: 2021-09-05 18:26 – Updated: 2025-11-04 00:12

Summary

Severity

No CVSS data available.

CWE

Assigner

mitre mitre root

References

4 references

URL	Tags
https://github.com/jedisct1/pure-ftpd/pull/158	x_refsource_MISC
https://github.com/jedisct1/pure-ftpd/compare/1.0…	x_refsource_CONFIRM
https://github.com/jedisct1/pure-ftpd/commit/37ad…	x_refsource_CONFIRM
https://lists.debian.org/debian-lts-announce/2025…

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "providerMetadata": {
          "dateUpdated": "2025-11-04T00:12:03.856Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
          "shortName": "CVE"
        },
        "references": [
          {
            "tags": [
              "x_refsource_MISC",
              "x_transferred"
            ],
            "url": "https://github.com/jedisct1/pure-ftpd/pull/158"
          },
          {
            "tags": [
              "x_refsource_CONFIRM",
              "x_transferred"
            ],
            "url": "https://github.com/jedisct1/pure-ftpd/compare/1.0.49...1.0.50"
          },
          {
            "tags": [
              "x_refsource_CONFIRM",
              "x_transferred"
            ],
            "url": "https://github.com/jedisct1/pure-ftpd/commit/37ad222868e52271905b94afea4fc780d83294b4"
          },
          {
            "url": "https://lists.debian.org/debian-lts-announce/2025/11/msg00003.html"
          }
        ],
        "title": "CVE Program Container"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "n/a",
          "vendor": "n/a",
          "versions": [
            {
              "status": "affected",
              "version": "n/a"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "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.)"
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "description": "n/a",
              "lang": "en",
              "type": "text"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2021-11-24T08:14:24.000Z",
        "orgId": "8254265b-2729-46b6-b9e3-3dfca2d5bfca",
        "shortName": "mitre"
      },
      "references": [
        {
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/jedisct1/pure-ftpd/pull/158"
        },
        {
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/jedisct1/pure-ftpd/compare/1.0.49...1.0.50"
        },
        {
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/jedisct1/pure-ftpd/commit/37ad222868e52271905b94afea4fc780d83294b4"
        }
      ],
      "x_legacyV4Record": {
        "CVE_data_meta": {
          "ASSIGNER": "cve@mitre.org",
          "ID": "CVE-2021-40524",
          "STATE": "PUBLIC"
        },
        "affects": {
          "vendor": {
            "vendor_data": [
              {
                "product": {
                  "product_data": [
                    {
                      "product_name": "n/a",
                      "version": {
                        "version_data": [
                          {
                            "version_value": "n/a"
                          }
                        ]
                      }
                    }
                  ]
                },
                "vendor_name": "n/a"
              }
            ]
          }
        },
        "data_format": "MITRE",
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        "data_version": "4.0",
        "description": {
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            }
          ]
        },
        "problemtype": {
          "problemtype_data": [
            {
              "description": [
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                  "value": "n/a"
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        "references": {
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              "refsource": "MISC",
              "url": "https://github.com/jedisct1/pure-ftpd/pull/158"
            },
            {
              "name": "https://github.com/jedisct1/pure-ftpd/compare/1.0.49...1.0.50",
              "refsource": "CONFIRM",
              "url": "https://github.com/jedisct1/pure-ftpd/compare/1.0.49...1.0.50"
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            {
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  "cveMetadata": {
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    "assignerShortName": "mitre",
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    "datePublished": "2021-09-05T18:26:26.000Z",
    "dateReserved": "2021-09-05T00:00:00.000Z",
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}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.