High
zookeeper — security advisory
Hostname verification in Apache ZooKeeper ZKTrustManager falls back to reverse DNS (PTR) when IP SAN validation fails, allowing attackers who control or spoof PTR records to impersonate ZooKeeper servers or clients with a valid certificate for the PTR name. It's important to note that attacker must present a certificate which is trusted by ZKTrustManager which makes the attack vector harder to exploit. Users are recommended to upgrade to version 3.8.6 or 3.9.5, which fixes this issue by introducing a new configuration option to disable reverse DNS lookup in client and quorum protocols.
- Products
- zookeeper
- Affected versions
- 3.4.10-2, 3.4.10-3, 3.4.13-1, 3.4.13-3, 3.4.13-3build1, 3.4.13-3ubuntu0.1~esm1, 3.4.13-4, 3.4.13-5, 3.4.13-5build1, 3.4.13-5ubuntu0.1, 3.4.13-5ubuntu4, 3.4.13-6ubuntu2, 3.4.13-6ubuntu3, 3.4.13-6ubuntu4, 3.4.13-6ubuntu4.1, 3.4.5+dfsg-1, 3.4.5+dfsg-1ubuntu0.1~esm1, 3.4.5+dfsg-1ubuntu0.1~esm3, 3.4.6-8, 3.4.7-1, 3.4.8-1, 3.4.8-1ubuntu0.1~esm1, 3.4.8-1ubuntu0.1~esm2, 3.8.0-11, 3.9.1-1, 3.9.1-1build1, 3.9.1-1build2, 3.9.3-1build1, 3.9.3-1build2, 3.9.3-1build3, 3.9.4-1, 3.9.5-1, 3.9.5-2
- Fixed versions
- Not specified
- CVEs
- CVE-2026-24281
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 02:58 UTC · Revision 1
Source evidence
Hostname verification in Apache ZooKeeper ZKTrustManager falls back to reverse DNS (PTR) when IP SAN validation fails, allowing attackers who control or spoof PTR records to impersonate ZooKeeper servers or clients with a valid certificate for the PTR name. It's important to note that attacker must present a certificate which is trusted by ZKTrustManager which makes the attack vector harder to exploit. Users are recommended to upgrade to version 3.8.6 or 3.9.5, which fixes this issue by introducing a new configuration option to disable reverse DNS lookup in client and quorum protocols.
osv:UBUNTU-CVE-2026-24281
zookeeper
Fixed versions: Not specified
zookeeper
Fixed versions: Not specified
zookeeper
Fixed versions: Not specified
zookeeper
Fixed versions: Not specified
zookeeper
Fixed versions: Not specified
zookeeper
Fixed versions: Not specified
zookeeper
Fixed versions: Not specified
zookeeper
Fixed versions: Not specified
zookeeper
Fixed versions: Not specified
Complete source record
{
"id": "4295fa4a43646634b95d7a9a7c10341d917c1cfd89e36a67e8ed8eb335b2d696",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-24281",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2026-24281",
"summary": "Hostname verification in Apache ZooKeeper ZKTrustManager falls back to reverse DNS (PTR) when IP SAN validation fails, allowing attackers who control or spoof PTR records to impersonate ZooKeeper servers or clients with a valid certificate for the PTR name. It's important to note that attacker must present a certificate which is trusted by ZKTrustManager which makes the attack vector harder to exploit. Users are recommended to upgrade to version 3.8.6 or 3.9.5, which fixes this issue by introducing a new configuration option to disable reverse DNS lookup in client and quorum protocols.",
"evidence": "osv:UBUNTU-CVE-2026-24281",
"products": [
{
"name": {
"value": "zookeeper",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "3.4.5+dfsg-1",
"evidence": "/affected/0/versions"
},
{
"value": "3.4.5+dfsg-1ubuntu0.1~esm1",
"evidence": "/affected/0/versions"
},
{
"value": "3.4.5+dfsg-1ubuntu0.1~esm3",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
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"evidence": "/affected/1/package/name"
},
"prerequisites": [],
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"affected_versions": [
{
"value": "3.4.6-8",
"evidence": "/affected/1/versions"
},
{
"value": "3.4.7-1",
"evidence": "/affected/1/versions"
},
{
"value": "3.4.8-1",
"evidence": "/affected/1/versions"
},
{
"value": "3.4.8-1ubuntu0.1~esm1",
"evidence": "/affected/1/versions"
},
{
"value": "3.4.8-1ubuntu0.1~esm2",
"evidence": "/affected/1/versions"
}
]
},
{
"name": {
"value": "zookeeper",
"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "3.4.10-2",
"evidence": "/affected/2/versions"
},
{
"value": "3.4.10-3",
"evidence": "/affected/2/versions"
},
{
"value": "3.4.13-3",
"evidence": "/affected/2/versions"
},
{
"value": "3.4.13-3ubuntu0.1~esm1",
"evidence": "/affected/2/versions"
}
]
},
{
"name": {
"value": "zookeeper",
"evidence": "/affected/3/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "3.4.13-1",
"evidence": "/affected/3/versions"
},
{
"value": "3.4.13-3",
"evidence": "/affected/3/versions"
},
{
"value": "3.4.13-3build1",
"evidence": "/affected/3/versions"
},
{
"value": "3.4.13-4",
"evidence": "/affected/3/versions"
},
{
"value": "3.4.13-5",
"evidence": "/affected/3/versions"
},
{
"value": "3.4.13-5build1",
"evidence": "/affected/3/versions"
},
{
"value": "3.4.13-5ubuntu0.1",
"evidence": "/affected/3/versions"
}
]
},
{
"name": {
"value": "zookeeper",
"evidence": "/affected/4/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "3.4.13-5ubuntu4",
"evidence": "/affected/4/versions"
},
{
"value": "3.4.13-6ubuntu2",
"evidence": "/affected/4/versions"
},
{
"value": "3.4.13-6ubuntu3",
"evidence": "/affected/4/versions"
},
{
"value": "3.4.13-6ubuntu4",
"evidence": "/affected/4/versions"
},
{
"value": "3.4.13-6ubuntu4.1",
"evidence": "/affected/4/versions"
}
]
},
{
"name": {
"value": "zookeeper",
"evidence": "/affected/5/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "3.8.0-11",
"evidence": "/affected/5/versions"
},
{
"value": "3.9.1-1",
"evidence": "/affected/5/versions"
},
{
"value": "3.9.1-1build1",
"evidence": "/affected/5/versions"
},
{
"value": "3.9.1-1build2",
"evidence": "/affected/5/versions"
}
]
},
{
"name": {
"value": "zookeeper",
"evidence": "/affected/6/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "3.9.3-1build1",
"evidence": "/affected/6/versions"
},
{
"value": "3.9.3-1build2",
"evidence": "/affected/6/versions"
}
]
},
{
"name": {
"value": "zookeeper",
"evidence": "/affected/7/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "3.9.5-1",
"evidence": "/affected/7/versions"
},
{
"value": "3.9.5-2",
"evidence": "/affected/7/versions"
}
]
},
{
"name": {
"value": "zookeeper",
"evidence": "/affected/8/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "3.9.3-1build2",
"evidence": "/affected/8/versions"
},
{
"value": "3.9.3-1build3",
"evidence": "/affected/8/versions"
},
{
"value": "3.9.4-1",
"evidence": "/affected/8/versions"
},
{
"value": "3.9.5-1",
"evidence": "/affected/8/versions"
}
]
}
],
"severity": "high",
"structured": {
"id": "UBUNTU-CVE-2026-24281",
"aliases": [
"UBUNTU-CVE-2026-24281"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N"
},
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N"
},
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N"
},
{
"type": "Ubuntu",
"score": "medium"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "zookeeper",
"purl": "pkg:deb/ubuntu/zookeeper?arch=source&distro=esm-infra-legacy%2Ftrusty",
"ecosystem": "Ubuntu:Pro:14.04:LTS"
},
"versions": [
"3.4.5+dfsg-1",
"3.4.5+dfsg-1ubuntu0.1~esm1",
"3.4.5+dfsg-1ubuntu0.1~esm3"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-24281.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libzookeeper-java",
"binary_version": "3.4.5+dfsg-1ubuntu0.1~esm3"
},
{
"binary_name": "libzookeeper-mt2",
"binary_version": "3.4.5+dfsg-1ubuntu0.1~esm3"
},
{
"binary_name": "libzookeeper-st2",
"binary_version": "3.4.5+dfsg-1ubuntu0.1~esm3"
},
{
"binary_name": "libzookeeper2",
"binary_version": "3.4.5+dfsg-1ubuntu0.1~esm3"
},
{
"binary_name": "python-zookeeper",
"binary_version": "3.4.5+dfsg-1ubuntu0.1~esm3"
},
{
"binary_name": "zookeeper",
"binary_version": "3.4.5+dfsg-1ubuntu0.1~esm3"
},
{
"binary_name": "zookeeper-bin",
"binary_version": "3.4.5+dfsg-1ubuntu0.1~esm3"
},
{
"binary_name": "zookeeperd",
"binary_version": "3.4.5+dfsg-1ubuntu0.1~esm3"
}
]
}
},
{
"ranges": [
{
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{
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}
]
}
],
"package": {
"name": "zookeeper",
"purl": "pkg:deb/ubuntu/zookeeper?arch=source&distro=esm-apps%2Fxenial",
"ecosystem": "Ubuntu:Pro:16.04:LTS"
},
"versions": [
"3.4.6-8",
"3.4.7-1",
"3.4.8-1",
"3.4.8-1ubuntu0.1~esm1",
"3.4.8-1ubuntu0.1~esm2"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-24281.json"
},
"ecosystem_specific": {
"binaries": [
{
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"binary_version": "3.4.8-1ubuntu0.1~esm2"
},
{
"binary_name": "libzookeeper-mt2",
"binary_version": "3.4.8-1ubuntu0.1~esm2"
},
{
"binary_name": "libzookeeper-st2",
"binary_version": "3.4.8-1ubuntu0.1~esm2"
},
{
"binary_name": "libzookeeper2",
"binary_version": "3.4.8-1ubuntu0.1~esm2"
},
{
"binary_name": "python-zookeeper",
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},
{
"binary_name": "zookeeper",
"binary_version": "3.4.8-1ubuntu0.1~esm2"
},
{
"binary_name": "zookeeper-bin",
"binary_version": "3.4.8-1ubuntu0.1~esm2"
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{
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}
]
}
},
{
"ranges": [
{
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}
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}
],
"package": {
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"ecosystem": "Ubuntu:Pro:18.04:LTS"
},
"versions": [
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"3.4.10-3",
"3.4.13-3",
"3.4.13-3ubuntu0.1~esm1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-24281.json"
},
"ecosystem_specific": {
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{
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},
{
"binary_name": "libzookeeper-mt2",
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},
{
"binary_name": "libzookeeper-st2",
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},
{
"binary_name": "python-zookeeper",
"binary_version": "3.4.13-3ubuntu0.1~esm1"
},
{
"binary_name": "zookeeper",
"binary_version": "3.4.13-3ubuntu0.1~esm1"
},
{
"binary_name": "zookeeper-bin",
"binary_version": "3.4.13-3ubuntu0.1~esm1"
},
{
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}
]
}
},
{
"ranges": [
{
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{
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}
]
}
],
"package": {
"name": "zookeeper",
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"ecosystem": "Ubuntu:20.04:LTS"
},
"versions": [
"3.4.13-1",
"3.4.13-3",
"3.4.13-3build1",
"3.4.13-4",
"3.4.13-5",
"3.4.13-5build1",
"3.4.13-5ubuntu0.1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-24281.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libzookeeper-java",
"binary_version": "3.4.13-5ubuntu0.1"
},
{
"binary_name": "libzookeeper-mt2",
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},
{
"binary_name": "libzookeeper-st2",
"binary_version": "3.4.13-5ubuntu0.1"
},
{
"binary_name": "python3-zookeeper",
"binary_version": "3.4.13-5ubuntu0.1"
},
{
"binary_name": "zookeeper",
"binary_version": "3.4.13-5ubuntu0.1"
},
{
"binary_name": "zookeeper-bin",
"binary_version": "3.4.13-5ubuntu0.1"
},
{
"binary_name": "zookeeperd",
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}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
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{
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}
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}
],
"package": {
"name": "zookeeper",
"purl": "pkg:deb/ubuntu/zookeeper?arch=source&distro=jammy",
"ecosystem": "Ubuntu:22.04:LTS"
},
"versions": [
"3.4.13-5ubuntu4",
"3.4.13-6ubuntu2",
"3.4.13-6ubuntu3",
"3.4.13-6ubuntu4",
"3.4.13-6ubuntu4.1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-24281.json"
},
"ecosystem_specific": {
"binaries": [
{
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"binary_version": "3.4.13-6ubuntu4.1"
},
{
"binary_name": "libzookeeper-mt2",
"binary_version": "3.4.13-6ubuntu4.1"
},
{
"binary_name": "libzookeeper-st2",
"binary_version": "3.4.13-6ubuntu4.1"
},
{
"binary_name": "python3-zookeeper",
"binary_version": "3.4.13-6ubuntu4.1"
},
{
"binary_name": "zookeeper",
"binary_version": "3.4.13-6ubuntu4.1"
},
{
"binary_name": "zookeeper-bin",
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},
{
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}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
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}
]
}
],
"package": {
"name": "zookeeper",
"purl": "pkg:deb/ubuntu/zookeeper?arch=source&distro=noble",
"ecosystem": "Ubuntu:24.04:LTS"
},
"versions": [
"3.8.0-11",
"3.9.1-1",
"3.9.1-1build1",
"3.9.1-1build2"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-24281.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libzookeeper-java",
"binary_version": "3.9.1-1build2"
},
{
"binary_name": "libzookeeper-mt2",
"binary_version": "3.9.1-1build2"
},
{
"binary_name": "libzookeeper-st2",
"binary_version": "3.9.1-1build2"
},
{
"binary_name": "python3-zookeeper",
"binary_version": "3.9.1-1build2"
},
{
"binary_name": "zookeeper",
"binary_version": "3.9.1-1build2"
},
{
"binary_name": "zookeeper-bin",
"binary_version": "3.9.1-1build2"
},
{
"binary_name": "zookeeperd",
"binary_version": "3.9.1-1build2"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "zookeeper",
"purl": "pkg:deb/ubuntu/zookeeper?arch=source&distro=questing",
"ecosystem": "Ubuntu:25.10"
},
"versions": [
"3.9.3-1build1",
"3.9.3-1build2"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-24281.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libzookeeper-java",
"binary_version": "3.9.3-1build2"
},
{
"binary_name": "libzookeeper-mt2",
"binary_version": "3.9.3-1build2"
},
{
"binary_name": "libzookeeper-st2",
"binary_version": "3.9.3-1build2"
},
{
"binary_name": "python3-zookeeper",
"binary_version": "3.9.3-1build2"
},
{
"binary_name": "zookeeper",
"binary_version": "3.9.3-1build2"
},
{
"binary_name": "zookeeper-bin",
"binary_version": "3.9.3-1build2"
},
{
"binary_name": "zookeeperd",
"binary_version": "3.9.3-1build2"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "zookeeper",
"purl": "pkg:deb/ubuntu/zookeeper?arch=source&distro=stonking",
"ecosystem": "Ubuntu:26.10"
},
"versions": [
"3.9.5-1",
"3.9.5-2"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-24281.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libzookeeper-java",
"binary_version": "3.9.5-2"
},
{
"binary_name": "libzookeeper-mt2",
"binary_version": "3.9.5-2"
},
{
"binary_name": "libzookeeper-st2",
"binary_version": "3.9.5-2"
},
{
"binary_name": "python3-zookeeper",
"binary_version": "3.9.5-2"
},
{
"binary_name": "zookeeper",
"binary_version": "3.9.5-2"
},
{
"binary_name": "zookeeper-bin",
"binary_version": "3.9.5-2"
},
{
"binary_name": "zookeeperd",
"binary_version": "3.9.5-2"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "zookeeper",
"purl": "pkg:deb/ubuntu/zookeeper?arch=source&distro=resolute",
"ecosystem": "Ubuntu:26.04:LTS"
},
"versions": [
"3.9.3-1build2",
"3.9.3-1build3",
"3.9.4-1",
"3.9.5-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-24281.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libzookeeper-java",
"binary_version": "3.9.5-1"
},
{
"binary_name": "libzookeeper-mt2",
"binary_version": "3.9.5-1"
},
{
"binary_name": "libzookeeper-st2",
"binary_version": "3.9.5-1"
},
{
"binary_name": "python3-zookeeper",
"binary_version": "3.9.5-1"
},
{
"binary_name": "zookeeper",
"binary_version": "3.9.5-1"
},
{
"binary_name": "zookeeper-bin",
"binary_version": "3.9.5-1"
},
{
"binary_name": "zookeeperd",
"binary_version": "3.9.5-1"
}
]
}
}
],
"modified": "2026-10-17T12:59:56.126450234Z",
"provider": "osv",
"upstream": [
"CVE-2026-24281"
],
"references": [
"https://ubuntu.com/security/CVE-2026-24281",
"https://www.cve.org/CVERecord?id=CVE-2026-24281",
"https://lists.apache.org/thread/088ddsbrzhd5lxzbqf5n24yg0mwh9jt2"
]
},
"related_cves": [
{
"value": "CVE-2026-24281",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 359990,
"published_at": "2026-03-07T09:16:00+00:00"
}