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.
Advisories

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Fixes

Solution

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Workaround

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History

Thu, 17 Sep 2026 21:15:00 +0000

Type Values Removed Values Added
First Time appeared Apache
Apache zookeeper
Vendors & Products Apache
Apache zookeeper

Thu, 17 Sep 2026 20:30:00 +0000

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N'}

ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Wed, 16 Sep 2026 11:30:00 +0000

Type Values Removed Values Added
References

Wed, 16 Sep 2026 09:45:00 +0000

Type Values Removed Values Added
Description 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.
Title Apache ZooKeeper: Improper validation of certificate with host mismatch in FIPS mode
Weaknesses CWE-297
References

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: apache

Published:

Updated: 2026-09-17T19:17:01.444Z

Reserved: 2026-07-07T18:50:40.959Z

Link: CVE-2026-59969

cve-icon Vulnrichment

Updated: 2026-09-17T19:16:56.939Z

cve-icon NVD

Status : Undergoing Analysis

Published: 2026-09-16T10:16:51.220

Modified: 2026-09-17T20:16:54.047

Link: CVE-2026-59969

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-09-17T20:49:54Z

Weaknesses