Medium
dnsdist — security advisory
An attacker can send crafted DNS over HTTP/3 queries, triggering an exception that prevents some buffer from being freed right away. The buffer will be freed at the end of the QUIC connection, but on some setups it might be possible to open enough concurrent DoH3 streams to trigger an out-of-memory condition, resulting in a denial of service.
- Products
- dnsdist
- Affected versions
- 1.0.0~alpha2-1, 1.2.0-1, 1.2.0-3, 1.2.1-1, 1.2.1-1build1, 1.2.1-1ubuntu0.1~esm1, 1.4.0-1, 1.4.0-1build1, 1.4.0-1build2, 1.4.0-1ubuntu0.1~esm1, 1.4.0~rc3-1, 1.5.1-3build2, 1.6.1-1build1, 1.6.1-1ubuntu0.1~esm1, 1.6.1-1ubuntu0.1~esm2, 1.8.0-1, 1.8.2-1, 1.8.2-2, 1.8.2-3, 1.8.3-1, 1.8.3-2, 1.8.3-2build1, 1.8.3-2build2, 1.8.3-2ubuntu0.1~esm1, 1.9.10-1, 1.9.10-1ubuntu0.1, 1.9.8-1, 2.0.1-1, 2.0.2-1, 2.0.2-1build1, 2.0.5-2ubuntu1, 2.0.5-2ubuntu3
- Fixed versions
- Not specified
- CVEs
- CVE-2026-40211
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 02:43 UTC · Revision 1
Source evidence
An attacker can send crafted DNS over HTTP/3 queries, triggering an exception that prevents some buffer from being freed right away. The buffer will be freed at the end of the QUIC connection, but on some setups it might be possible to open enough concurrent DoH3 streams to trigger an out-of-memory condition, resulting in a denial of service.
osv:UBUNTU-CVE-2026-40211
dnsdist
Fixed versions: Not specified
dnsdist
Fixed versions: Not specified
dnsdist
Fixed versions: Not specified
dnsdist
Fixed versions: Not specified
dnsdist
Fixed versions: Not specified
dnsdist
Fixed versions: Not specified
dnsdist
Fixed versions: Not specified
dnsdist
Fixed versions: Not specified
Complete source record
{
"id": "b57c50bf13924477dd9dcfef735eb6e699f589ec89d1bfc1d6bc9bcc76027c61",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-40211",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2026-40211",
"summary": "An attacker can send crafted DNS over HTTP/3 queries, triggering an exception that prevents some buffer from being freed right away. The buffer will be freed at the end of the QUIC connection, but on some setups it might be possible to open enough concurrent DoH3 streams to trigger an out-of-memory condition, resulting in a denial of service.",
"evidence": "osv:UBUNTU-CVE-2026-40211",
"products": [
{
"name": {
"value": "dnsdist",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.0.0~alpha2-1",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
"value": "dnsdist",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.2.0-1",
"evidence": "/affected/1/versions"
},
{
"value": "1.2.0-3",
"evidence": "/affected/1/versions"
},
{
"value": "1.2.1-1",
"evidence": "/affected/1/versions"
},
{
"value": "1.2.1-1build1",
"evidence": "/affected/1/versions"
},
{
"value": "1.2.1-1ubuntu0.1~esm1",
"evidence": "/affected/1/versions"
}
]
},
{
"name": {
"value": "dnsdist",
"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.4.0~rc3-1",
"evidence": "/affected/2/versions"
},
{
"value": "1.4.0-1",
"evidence": "/affected/2/versions"
},
{
"value": "1.4.0-1build1",
"evidence": "/affected/2/versions"
},
{
"value": "1.4.0-1build2",
"evidence": "/affected/2/versions"
},
{
"value": "1.4.0-1ubuntu0.1~esm1",
"evidence": "/affected/2/versions"
}
]
},
{
"name": {
"value": "dnsdist",
"evidence": "/affected/3/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.5.1-3build2",
"evidence": "/affected/3/versions"
},
{
"value": "1.6.1-1build1",
"evidence": "/affected/3/versions"
},
{
"value": "1.6.1-1ubuntu0.1~esm1",
"evidence": "/affected/3/versions"
},
{
"value": "1.6.1-1ubuntu0.1~esm2",
"evidence": "/affected/3/versions"
}
]
},
{
"name": {
"value": "dnsdist",
"evidence": "/affected/4/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.8.0-1",
"evidence": "/affected/4/versions"
},
{
"value": "1.8.2-1",
"evidence": "/affected/4/versions"
},
{
"value": "1.8.2-2",
"evidence": "/affected/4/versions"
},
{
"value": "1.8.2-3",
"evidence": "/affected/4/versions"
},
{
"value": "1.8.3-1",
"evidence": "/affected/4/versions"
},
{
"value": "1.8.3-2",
"evidence": "/affected/4/versions"
},
{
"value": "1.8.3-2build1",
"evidence": "/affected/4/versions"
},
{
"value": "1.8.3-2build2",
"evidence": "/affected/4/versions"
},
{
"value": "1.8.3-2ubuntu0.1~esm1",
"evidence": "/affected/4/versions"
}
]
},
{
"name": {
"value": "dnsdist",
"evidence": "/affected/5/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.9.8-1",
"evidence": "/affected/5/versions"
},
{
"value": "1.9.10-1",
"evidence": "/affected/5/versions"
},
{
"value": "1.9.10-1ubuntu0.1",
"evidence": "/affected/5/versions"
}
]
},
{
"name": {
"value": "dnsdist",
"evidence": "/affected/6/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "2.0.2-1build1",
"evidence": "/affected/6/versions"
},
{
"value": "2.0.5-2ubuntu1",
"evidence": "/affected/6/versions"
},
{
"value": "2.0.5-2ubuntu3",
"evidence": "/affected/6/versions"
}
]
},
{
"name": {
"value": "dnsdist",
"evidence": "/affected/7/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.9.10-1",
"evidence": "/affected/7/versions"
},
{
"value": "2.0.1-1",
"evidence": "/affected/7/versions"
},
{
"value": "2.0.2-1",
"evidence": "/affected/7/versions"
},
{
"value": "2.0.2-1build1",
"evidence": "/affected/7/versions"
}
]
}
],
"severity": "medium",
"structured": {
"id": "UBUNTU-CVE-2026-40211",
"aliases": [
"UBUNTU-CVE-2026-40211"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"
},
{
"type": "Ubuntu",
"score": "medium"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "dnsdist",
"purl": "pkg:deb/ubuntu/dnsdist?arch=source&distro=xenial",
"ecosystem": "Ubuntu:16.04:LTS"
},
"versions": [
"1.0.0~alpha2-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-40211.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "dnsdist",
"binary_version": "1.0.0~alpha2-1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "dnsdist",
"purl": "pkg:deb/ubuntu/dnsdist?arch=source&distro=esm-apps%2Fbionic",
"ecosystem": "Ubuntu:Pro:18.04:LTS"
},
"versions": [
"1.2.0-1",
"1.2.0-3",
"1.2.1-1",
"1.2.1-1build1",
"1.2.1-1ubuntu0.1~esm1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-40211.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "dnsdist",
"binary_version": "1.2.1-1ubuntu0.1~esm1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "dnsdist",
"purl": "pkg:deb/ubuntu/dnsdist?arch=source&distro=esm-apps%2Ffocal",
"ecosystem": "Ubuntu:Pro:20.04:LTS"
},
"versions": [
"1.4.0~rc3-1",
"1.4.0-1",
"1.4.0-1build1",
"1.4.0-1build2",
"1.4.0-1ubuntu0.1~esm1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-40211.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "dnsdist",
"binary_version": "1.4.0-1ubuntu0.1~esm1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "dnsdist",
"purl": "pkg:deb/ubuntu/dnsdist?arch=source&distro=esm-apps%2Fjammy",
"ecosystem": "Ubuntu:Pro:22.04:LTS"
},
"versions": [
"1.5.1-3build2",
"1.6.1-1build1",
"1.6.1-1ubuntu0.1~esm1",
"1.6.1-1ubuntu0.1~esm2"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-40211.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "dnsdist",
"binary_version": "1.6.1-1ubuntu0.1~esm2"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "dnsdist",
"purl": "pkg:deb/ubuntu/dnsdist?arch=source&distro=esm-apps%2Fnoble",
"ecosystem": "Ubuntu:Pro:24.04:LTS"
},
"versions": [
"1.8.0-1",
"1.8.2-1",
"1.8.2-2",
"1.8.2-3",
"1.8.3-1",
"1.8.3-2",
"1.8.3-2build1",
"1.8.3-2build2",
"1.8.3-2ubuntu0.1~esm1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-40211.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "dnsdist",
"binary_version": "1.8.3-2ubuntu0.1~esm1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "dnsdist",
"purl": "pkg:deb/ubuntu/dnsdist?arch=source&distro=questing",
"ecosystem": "Ubuntu:25.10"
},
"versions": [
"1.9.8-1",
"1.9.10-1",
"1.9.10-1ubuntu0.1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-40211.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "dnsdist",
"binary_version": "1.9.10-1ubuntu0.1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "dnsdist",
"purl": "pkg:deb/ubuntu/dnsdist?arch=source&distro=stonking",
"ecosystem": "Ubuntu:26.10"
},
"versions": [
"2.0.2-1build1",
"2.0.5-2ubuntu1",
"2.0.5-2ubuntu3"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-40211.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "dnsdist",
"binary_version": "2.0.5-2ubuntu3"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "dnsdist",
"purl": "pkg:deb/ubuntu/dnsdist?arch=source&distro=resolute",
"ecosystem": "Ubuntu:26.04:LTS"
},
"versions": [
"1.9.10-1",
"2.0.1-1",
"2.0.2-1",
"2.0.2-1build1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-40211.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "dnsdist",
"binary_version": "2.0.2-1build1"
}
]
}
}
],
"modified": "2026-10-17T12:58:53.965243178Z",
"provider": "osv",
"upstream": [
"CVE-2026-40211"
],
"references": [
"https://ubuntu.com/security/CVE-2026-40211",
"https://www.cve.org/CVERecord?id=CVE-2026-40211",
"https://www.dnsdist.org/security-advisories/powerdns-advisory-for-dnsdist-2026-09.html#cve-2026-40211-denial-of-service-via-crafted-doh3-queries"
]
},
"related_cves": [
{
"value": "CVE-2026-40211",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 359148,
"published_at": "2026-06-25T13:16:00+00:00"
}