High
zookeeper — security advisory
Apache ZooKeeper quorum TLS fails to enforce peer hostname verification in FIPS-mode deployments. When sslQuorum=true, zookeeper.fips-mode=true, ssl.quorum.hostnameVerification=true, and ssl.quorum.clientHostnameVerification=true are enabled, the Java SSLSocket quorum path accepts a CA-trusted peer certificate whose SAN does not match the connected host. A malicious or misissued peer certificate can therefore join quorum traffic, participate in leader election, and enter replication flows. Users are recommended to upgrade to version 3.8.7 or 3.9.6, which fixes the issue.
- 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, 3.9.3-1build2, 3.9.3-1build3, 3.9.4-1, 3.9.5-1, 3.9.5-2
- Fixed versions
- Not specified
- CVEs
- CVE-2026-59969
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 00:43 UTC · Revision 1
Source evidence
Apache ZooKeeper quorum TLS fails to enforce peer hostname verification in FIPS-mode deployments. When sslQuorum=true, zookeeper.fips-mode=true, ssl.quorum.hostnameVerification=true, and ssl.quorum.clientHostnameVerification=true are enabled, the Java SSLSocket quorum path accepts a CA-trusted peer certificate whose SAN does not match the connected host. A malicious or misissued peer certificate can therefore join quorum traffic, participate in leader election, and enter replication flows. Users are recommended to upgrade to version 3.8.7 or 3.9.6, which fixes the issue.
osv:UBUNTU-CVE-2026-59969
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": "33737630f8599e03e62ebf6ea4415d7f46bdd42b074babf8f64f5f63649215d7",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-59969",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2026-59969",
"summary": "Apache ZooKeeper quorum TLS fails to enforce peer hostname verification in FIPS-mode deployments. When sslQuorum=true, zookeeper.fips-mode=true, ssl.quorum.hostnameVerification=true, and ssl.quorum.clientHostnameVerification=true are enabled, the Java SSLSocket quorum path accepts a CA-trusted peer certificate whose SAN does not match the connected host. A malicious or misissued peer certificate can therefore join quorum traffic, participate in leader election, and enter replication flows. Users are recommended to upgrade to version 3.8.7 or 3.9.6, which fixes the issue.",
"evidence": "osv:UBUNTU-CVE-2026-59969",
"products": [
{
"name": {
"value": "zookeeper",
"evidence": "/affected/0/package/name"
},
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"affected_versions": [
{
"value": "3.4.5+dfsg-1",
"evidence": "/affected/0/versions"
},
{
"value": "3.4.5+dfsg-1ubuntu0.1~esm1",
"evidence": "/affected/0/versions"
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{
"value": "3.4.5+dfsg-1ubuntu0.1~esm3",
"evidence": "/affected/0/versions"
}
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{
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"evidence": "/affected/1/versions"
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{
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{
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{
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"evidence": "/affected/1/versions"
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{
"value": "3.4.8-1ubuntu0.1~esm2",
"evidence": "/affected/1/versions"
}
]
},
{
"name": {
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},
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{
"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"
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{
"name": {
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},
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"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": [],
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"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": "3.9.5-1",
"evidence": "/affected/6/versions"
},
{
"value": "3.9.5-2",
"evidence": "/affected/6/versions"
}
]
},
{
"name": {
"value": "zookeeper",
"evidence": "/affected/7/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "3.9.3-1build2",
"evidence": "/affected/7/versions"
},
{
"value": "3.9.3-1build3",
"evidence": "/affected/7/versions"
},
{
"value": "3.9.4-1",
"evidence": "/affected/7/versions"
},
{
"value": "3.9.5-1",
"evidence": "/affected/7/versions"
}
]
}
],
"severity": "high",
"structured": {
"id": "UBUNTU-CVE-2026-59969",
"aliases": [
"UBUNTU-CVE-2026-59969"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/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-2026-59969.json"
},
"ecosystem_specific": {
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{
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},
{
"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"
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{
"binary_name": "zookeeper-bin",
"binary_version": "3.4.5+dfsg-1ubuntu0.1~esm3"
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},
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"3.4.7-1",
"3.4.8-1",
"3.4.8-1ubuntu0.1~esm1",
"3.4.8-1ubuntu0.1~esm2"
],
"database_specific": {
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},
"ecosystem_specific": {
"binaries": [
{
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},
{
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"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",
"binary_version": "3.4.8-1ubuntu0.1~esm2"
},
{
"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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},
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{
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},
"ecosystem_specific": {
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{
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},
{
"binary_name": "libzookeeper-st2",
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},
{
"binary_name": "python3-zookeeper",
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},
{
"binary_name": "zookeeper",
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},
{
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},
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{
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],
"package": {
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"ecosystem": "Ubuntu:22.04:LTS"
},
"versions": [
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"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-2026-59969.json"
},
"ecosystem_specific": {
"binaries": [
{
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"binary_version": "3.4.13-6ubuntu4.1"
},
{
"binary_name": "libzookeeper-mt2",
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},
{
"binary_name": "libzookeeper-st2",
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},
{
"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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}
]
}
},
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"ecosystem": "Ubuntu:24.04:LTS"
},
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],
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},
"ecosystem_specific": {
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},
{
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},
{
"binary_name": "libzookeeper-st2",
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},
{
"binary_name": "python3-zookeeper",
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},
{
"binary_name": "zookeeper",
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},
{
"binary_name": "zookeeper-bin",
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},
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}
]
}
},
{
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},
"versions": [
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"3.9.5-2"
],
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},
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{
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},
{
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{
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},
{
"binary_name": "python3-zookeeper",
"binary_version": "3.9.5-2"
},
{
"binary_name": "zookeeper",
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},
{
"binary_name": "zookeeper-bin",
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{
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}
},
{
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{
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],
"package": {
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"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-2026-59969.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": "2026-10-17T12:56:00.380692755Z",
"provider": "osv",
"upstream": [
"CVE-2026-59969"
],
"references": [
"https://ubuntu.com/security/CVE-2026-59969",
"https://www.cve.org/CVERecord?id=CVE-2026-59969"
]
},
"related_cves": [
{
"value": "CVE-2026-59969",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 354529,
"published_at": "2026-09-16T10:16:00+00:00"
}