High
nsd — security advisory
Any remote client can crash a (debugging/non-release build type) NSD serve child by sending it a special crafted message with a specially tuned number of DNS Cookie options (17 when UDP payload size is 512). By continuously crashing the serve childs, the remote client can severely hamper or, when positioned sufficiently close, deny all DNS service.
- Products
- nsd
- Affected versions
- 4.1.16-1build1, 4.1.17-1, 4.1.17-1build1, 4.1.17-1ubuntu0.1~esm1, 4.1.2-1, 4.1.26-1, 4.1.26-1build1, 4.1.26-1ubuntu0.1~esm1, 4.1.6-1, 4.1.7-1, 4.1.7-1ubuntu0.1~esm1, 4.12.0-1, 4.13.0-6, 4.14.0-1, 4.14.0-1ubuntu0.1~esm1, 4.14.2-1, 4.14.3-1, 4.15.0-1, 4.15.0-1build1, 4.3.5-1, 4.3.7-1, 4.3.8-1, 4.3.8-1build1, 4.3.9-1, 4.3.9-1ubuntu0.1~esm1, 4.7.0-1, 4.8.0-1, 4.8.0-1build1, 4.8.0-1build3, 4.8.0-1ubuntu0.1~esm1
- Fixed versions
- Not specified
- CVEs
- CVE-2026-19401
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 02:55 UTC · Revision 1
Source evidence
Any remote client can crash a (debugging/non-release build type) NSD serve child by sending it a special crafted message with a specially tuned number of DNS Cookie options (17 when UDP payload size is 512). By continuously crashing the serve childs, the remote client can severely hamper or, when positioned sufficiently close, deny all DNS service.
osv:UBUNTU-CVE-2026-19401
nsd
Fixed versions: Not specified
nsd
Fixed versions: Not specified
nsd
Fixed versions: Not specified
nsd
Fixed versions: Not specified
nsd
Fixed versions: Not specified
nsd
Fixed versions: Not specified
nsd
Fixed versions: Not specified
Complete source record
{
"id": "6bcc934a83a6599589a317a632bd3bca6e2816eb9b729f836cb057260a8d3e66",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-19401",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2026-19401",
"summary": "Any remote client can crash a (debugging/non-release build type) NSD serve child by sending it a special crafted message with a specially tuned number of DNS Cookie options (17 when UDP payload size is 512). By continuously crashing the serve childs, the remote client can severely hamper or, when positioned sufficiently close, deny all DNS service.",
"evidence": "osv:UBUNTU-CVE-2026-19401",
"products": [
{
"name": {
"value": "nsd",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "4.1.2-1",
"evidence": "/affected/0/versions"
},
{
"value": "4.1.6-1",
"evidence": "/affected/0/versions"
},
{
"value": "4.1.7-1",
"evidence": "/affected/0/versions"
},
{
"value": "4.1.7-1ubuntu0.1~esm1",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
"value": "nsd",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "4.1.16-1build1",
"evidence": "/affected/1/versions"
},
{
"value": "4.1.17-1",
"evidence": "/affected/1/versions"
},
{
"value": "4.1.17-1build1",
"evidence": "/affected/1/versions"
},
{
"value": "4.1.17-1ubuntu0.1~esm1",
"evidence": "/affected/1/versions"
}
]
},
{
"name": {
"value": "nsd",
"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "4.1.26-1",
"evidence": "/affected/2/versions"
},
{
"value": "4.1.26-1build1",
"evidence": "/affected/2/versions"
},
{
"value": "4.1.26-1ubuntu0.1~esm1",
"evidence": "/affected/2/versions"
}
]
},
{
"name": {
"value": "nsd",
"evidence": "/affected/3/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "4.3.5-1",
"evidence": "/affected/3/versions"
},
{
"value": "4.3.7-1",
"evidence": "/affected/3/versions"
},
{
"value": "4.3.8-1",
"evidence": "/affected/3/versions"
},
{
"value": "4.3.8-1build1",
"evidence": "/affected/3/versions"
},
{
"value": "4.3.9-1",
"evidence": "/affected/3/versions"
},
{
"value": "4.3.9-1ubuntu0.1~esm1",
"evidence": "/affected/3/versions"
}
]
},
{
"name": {
"value": "nsd",
"evidence": "/affected/4/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "4.7.0-1",
"evidence": "/affected/4/versions"
},
{
"value": "4.8.0-1",
"evidence": "/affected/4/versions"
},
{
"value": "4.8.0-1build1",
"evidence": "/affected/4/versions"
},
{
"value": "4.8.0-1build3",
"evidence": "/affected/4/versions"
},
{
"value": "4.8.0-1ubuntu0.1~esm1",
"evidence": "/affected/4/versions"
}
]
},
{
"name": {
"value": "nsd",
"evidence": "/affected/5/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "4.14.0-1",
"evidence": "/affected/5/versions"
},
{
"value": "4.14.2-1",
"evidence": "/affected/5/versions"
},
{
"value": "4.14.3-1",
"evidence": "/affected/5/versions"
},
{
"value": "4.15.0-1",
"evidence": "/affected/5/versions"
},
{
"value": "4.15.0-1build1",
"evidence": "/affected/5/versions"
}
]
},
{
"name": {
"value": "nsd",
"evidence": "/affected/6/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "4.12.0-1",
"evidence": "/affected/6/versions"
},
{
"value": "4.13.0-6",
"evidence": "/affected/6/versions"
},
{
"value": "4.14.0-1",
"evidence": "/affected/6/versions"
},
{
"value": "4.14.0-1ubuntu0.1~esm1",
"evidence": "/affected/6/versions"
}
]
}
],
"severity": "high",
"structured": {
"id": "UBUNTU-CVE-2026-19401",
"aliases": [
"UBUNTU-CVE-2026-19401"
],
"metrics": [
{
"type": "CVSS_V4",
"score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"
},
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
},
{
"type": "Ubuntu",
"score": "medium"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "nsd",
"purl": "pkg:deb/ubuntu/nsd?arch=source&distro=esm-apps-legacy%2Fxenial",
"ecosystem": "Ubuntu:Pro:16.04:LTS"
},
"versions": [
"4.1.2-1",
"4.1.6-1",
"4.1.7-1",
"4.1.7-1ubuntu0.1~esm1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19401.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "nsd",
"binary_version": "4.1.7-1ubuntu0.1~esm1"
},
{
"binary_name": "nsd3",
"binary_version": "4.1.7-1ubuntu0.1~esm1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "nsd",
"purl": "pkg:deb/ubuntu/nsd?arch=source&distro=esm-apps%2Fbionic",
"ecosystem": "Ubuntu:Pro:18.04:LTS"
},
"versions": [
"4.1.16-1build1",
"4.1.17-1",
"4.1.17-1build1",
"4.1.17-1ubuntu0.1~esm1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19401.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "nsd",
"binary_version": "4.1.17-1ubuntu0.1~esm1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "nsd",
"purl": "pkg:deb/ubuntu/nsd?arch=source&distro=esm-apps%2Ffocal",
"ecosystem": "Ubuntu:Pro:20.04:LTS"
},
"versions": [
"4.1.26-1",
"4.1.26-1build1",
"4.1.26-1ubuntu0.1~esm1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19401.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "nsd",
"binary_version": "4.1.26-1ubuntu0.1~esm1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "nsd",
"purl": "pkg:deb/ubuntu/nsd?arch=source&distro=esm-apps%2Fjammy",
"ecosystem": "Ubuntu:Pro:22.04:LTS"
},
"versions": [
"4.3.5-1",
"4.3.7-1",
"4.3.8-1",
"4.3.8-1build1",
"4.3.9-1",
"4.3.9-1ubuntu0.1~esm1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19401.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "nsd",
"binary_version": "4.3.9-1ubuntu0.1~esm1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "nsd",
"purl": "pkg:deb/ubuntu/nsd?arch=source&distro=esm-apps%2Fnoble",
"ecosystem": "Ubuntu:Pro:24.04:LTS"
},
"versions": [
"4.7.0-1",
"4.8.0-1",
"4.8.0-1build1",
"4.8.0-1build3",
"4.8.0-1ubuntu0.1~esm1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19401.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "nsd",
"binary_version": "4.8.0-1ubuntu0.1~esm1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "nsd",
"purl": "pkg:deb/ubuntu/nsd?arch=source&distro=stonking",
"ecosystem": "Ubuntu:26.10"
},
"versions": [
"4.14.0-1",
"4.14.2-1",
"4.14.3-1",
"4.15.0-1",
"4.15.0-1build1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19401.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "nsd",
"binary_version": "4.15.0-1build1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "nsd",
"purl": "pkg:deb/ubuntu/nsd?arch=source&distro=esm-apps%2Fresolute",
"ecosystem": "Ubuntu:Pro:26.04:LTS"
},
"versions": [
"4.12.0-1",
"4.13.0-6",
"4.14.0-1",
"4.14.0-1ubuntu0.1~esm1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19401.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "nsd",
"binary_version": "4.14.0-1ubuntu0.1~esm1"
}
]
}
}
],
"modified": "2026-10-17T12:59:54.250760919Z",
"provider": "osv",
"upstream": [
"CVE-2026-19401"
],
"references": [
"https://ubuntu.com/security/CVE-2026-19401",
"https://www.cve.org/CVERecord?id=CVE-2026-19401"
]
},
"related_cves": [
{
"value": "CVE-2026-19401",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 359918,
"published_at": "2026-08-26T09:16:00+00:00"
}