MediumFix available
c-ares — security advisory
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
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"
}