Vulnerability-Lookup

FKIE_CVE-2020-21677

Vulnerability from fkie_nvd - Published: 2021-08-10 21:15 - Updated: 2026-06-17 03:03

Severity

6.5 (Medium) - CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Summary

A heap-based buffer overflow in the sixel_encoder_output_without_macro function in encoder.c of Libsixel 1.8.4 allows attackers to cause a denial of service (DOS) via converting a crafted PNG file into Sixel format.

References

	URL	Tags
	cve@mitre.org	https://github.com/saitoha/libsixel/issues/123	Exploit, Issue Tracking, Patch, Third Party Advisory
	af854a3a-2127-422b-91ae-364da2661108	https://github.com/saitoha/libsixel/issues/123	Exploit, Issue Tracking, Patch, Third Party Advisory

Impacted products

	Vendor	Product	Version
	saitoha	libsixel	1.8.4

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:saitoha:libsixel:1.8.4:*:*:*:*:*:*:*",
              "matchCriteriaId": "576C8904-2F54-4A56-86FF-C7A94C37061E",
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          ],
          "negate": false,
          "operator": "OR"
        }
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  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "A heap-based buffer overflow in the sixel_encoder_output_without_macro function in encoder.c of Libsixel 1.8.4 allows attackers to cause a denial of service (DOS) via converting a crafted PNG file into Sixel format."
    },
    {
      "lang": "es",
      "value": "Un desbordamiento de b\u00fafer en la regi\u00f3n heap de la memoria en la funci\u00f3n sixel_encoder_output_without_macro en el archivo  encoder.c de Libsixel versi\u00f3n 1.8.4, permite a atacantes causar una denegaci\u00f3n de servicio (DOS) por medio de la conversi\u00f3n de un archivo PNG dise\u00f1ado en formato Sixel"
    }
  ],
  "id": "CVE-2020-21677",
  "lastModified": "2026-06-17T03:03:51.470",
  "metrics": {
    "cvssMetricV2": [
      {
        "acInsufInfo": false,
        "baseSeverity": "MEDIUM",
        "cvssData": {
          "accessComplexity": "MEDIUM",
          "accessVector": "NETWORK",
          "authentication": "NONE",
          "availabilityImpact": "PARTIAL",
          "baseScore": 4.3,
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "vectorString": "AV:N/AC:M/Au:N/C:N/I:N/A:P",
          "version": "2.0"
        },
        "exploitabilityScore": 8.6,
        "impactScore": 2.9,
        "obtainAllPrivilege": false,
        "obtainOtherPrivilege": false,
        "obtainUserPrivilege": false,
        "source": "nvd@nist.gov",
        "type": "Primary",
        "userInteractionRequired": true
      }
    ],
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 6.5,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 3.6,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ]
  },
  "published": "2021-08-10T21:15:07.447",
  "references": [
    {
      "source": "cve@mitre.org",
      "tags": [
        "Exploit",
        "Issue Tracking",
        "Patch",
        "Third Party Advisory"
      ],
      "url": "https://github.com/saitoha/libsixel/issues/123"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Exploit",
        "Issue Tracking",
        "Patch",
        "Third Party Advisory"
      ],
      "url": "https://github.com/saitoha/libsixel/issues/123"
    }
  ],
  "sourceIdentifier": "cve@mitre.org",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-787"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}

CVE-2020-21677 (GCVE-0-2020-21677)

Vulnerability from cvelistv5 – Published: 2021-08-10 20:19 – Updated: 2024-08-04 14:30

Summary

Severity

No CVSS data available.

CWE

Assigner

mitre mitre root

References

1 reference

URL	Tags
https://github.com/saitoha/libsixel/issues/123	x_refsource_MISC

Show details on NVD website

JSON

To clipboard

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          "dateUpdated": "2024-08-04T14:30:33.580Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
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          {
            "tags": [
              "x_refsource_MISC",
              "x_transferred"
            ],
            "url": "https://github.com/saitoha/libsixel/issues/123"
          }
        ],
        "title": "CVE Program Container"
      }
    ],
    "cna": {
      "affected": [
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          "product": "n/a",
          "vendor": "n/a",
          "versions": [
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              "version": "n/a"
            }
          ]
        }
      ],
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          "value": "A heap-based buffer overflow in the sixel_encoder_output_without_macro function in encoder.c of Libsixel 1.8.4 allows attackers to cause a denial of service (DOS) via converting a crafted PNG file into Sixel format."
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "description": "n/a",
              "lang": "en",
              "type": "text"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2021-08-10T20:19:47.000Z",
        "orgId": "8254265b-2729-46b6-b9e3-3dfca2d5bfca",
        "shortName": "mitre"
      },
      "references": [
        {
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/saitoha/libsixel/issues/123"
        }
      ],
      "x_legacyV4Record": {
        "CVE_data_meta": {
          "ASSIGNER": "cve@mitre.org",
          "ID": "CVE-2020-21677",
          "STATE": "PUBLIC"
        },
        "affects": {
          "vendor": {
            "vendor_data": [
              {
                "product": {
                  "product_data": [
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                      "version": {
                        "version_data": [
                          {
                            "version_value": "n/a"
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                      }
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                "vendor_name": "n/a"
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        "data_version": "4.0",
        "description": {
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        },
        "problemtype": {
          "problemtype_data": [
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              "description": [
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              "refsource": "MISC",
              "url": "https://github.com/saitoha/libsixel/issues/123"
            }
          ]
        }
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "8254265b-2729-46b6-b9e3-3dfca2d5bfca",
    "assignerShortName": "mitre",
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    "datePublished": "2021-08-10T20:19:47.000Z",
    "dateReserved": "2020-08-13T00:00:00.000Z",
    "dateUpdated": "2024-08-04T14:30:33.580Z",
    "state": "PUBLISHED"
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  "dataType": "CVE_RECORD",
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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.