Vulnerability record · CVE-2026-59969 · published 16 September 2026

CVE-2026-59969: Apache zookeeper vulnerability

Apache · Zookeeper

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.

7.5 CVSS 3.1 High EPSS 0.33% · top 76.5% CWE-297 · CWE-297

7.5CVSS 3.1 base score

0.33%EPSS exploitation probability, 30 days

NoNot in CISA KEV

1Affected product versions listed by NVD

2References

18 Sep 2026Last modified by NVD

Description

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

Zookeeper Apache

References

Link	Tags
https://lists.apache.org/thread/qf9kwsgtgbgtvwls6f41281846xg0rss	Mailing ListVendor Advisory
http://www.openwall.com/lists/oss-security/2026/09/15/4	Mailing ListThird Party Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-59969), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.