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c-ares — security advisory

Type: advisorySources: OSVAdvisory ID: DEBIAN-CVE-2021-3672

A flaw was found in c-ares library, where a missing input validation check of host names returned by DNS (Domain Name Servers) can lead to output of wrong hostnames which might potentially lead to Domain Hijacking. The highest threat from this vulnerability is to confidentiality and integrity as well as system availability.

Products
c-ares
Affected versions
Not specified
Fixed versions
1.17.1-1.1
CVEs
CVE-2021-3672
Confirmed fixed CVEs
Not specified
Updated in this feed
1 Nov 2026, 00:36 UTC · Revision 1

Source evidence

DEBIAN-CVE-2021-3672

core-osv · Original source

Published 23 Nov 2021, 19:15 UTC

A flaw was found in c-ares library, where a missing input validation check of host names returned by DNS (Domain Name Servers) can lead to output of wrong hostnames which might potentially lead to Domain Hijacking. The highest threat from this vulnerability is to confidentiality and integrity as well as system availability.

osv:DEBIAN-CVE-2021-3672

c-ares

Fixed versions: 1.17.1-1.1

c-ares

Fixed versions: 1.17.1-1.1

c-ares

Fixed versions: 1.17.1-1.1

Complete source record
{
  "id": "371f1532638f501f313fb2e8909da95a2c125d7bc5316479e9fb58feb75a7e63",
  "url": "https://osv.dev/vulnerability/DEBIAN-CVE-2021-3672",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "DEBIAN-CVE-2021-3672",
    "summary": "A flaw was found in c-ares library, where a missing input validation check of host names returned by DNS (Domain Name Servers) can lead to output of wrong hostnames which might potentially lead to Domain Hijacking. The highest threat from this vulnerability is to confidentiality and integrity as well as system availability.",
    "evidence": "osv:DEBIAN-CVE-2021-3672",
    "products": [
      {
        "name": {
          "value": "c-ares",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1.17.1-1.1",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      },
      {
        "name": {
          "value": "c-ares",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1.17.1-1.1",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      },
      {
        "name": {
          "value": "c-ares",
          "evidence": "/affected/2/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1.17.1-1.1",
            "evidence": "/affected/2/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "DEBIAN-CVE-2021-3672",
      "aliases": [
        "DEBIAN-CVE-2021-3672"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "1.17.1-1.1"
                }
              ]
            }
          ],
          "package": {
            "name": "c-ares",
            "purl": "pkg:deb/debian/c-ares?arch=source&distro=bookworm",
            "ecosystem": "Debian:12"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2021-3672.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "1.17.1-1.1"
                }
              ]
            }
          ],
          "package": {
            "name": "c-ares",
            "purl": "pkg:deb/debian/c-ares?arch=source&distro=trixie",
            "ecosystem": "Debian:13"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2021-3672.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "1.17.1-1.1"
                }
              ]
            }
          ],
          "package": {
            "name": "c-ares",
            "purl": "pkg:deb/debian/c-ares?arch=source&distro=forky",
            "ecosystem": "Debian:14"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2021-3672.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        }
      ],
      "modified": "2026-10-23T18:03:29.681593637Z",
      "provider": "osv",
      "upstream": [
        "CVE-2021-3672"
      ],
      "references": [
        "https://security-tracker.debian.org/tracker/CVE-2021-3672"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2021-3672",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 421686,
  "published_at": "2021-11-23T19:15:07.877+00:00"
}