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CVE-2026-59969

Apache ZooKeeper: Improper validation of certificate with host mismatch in FIPS mode

Published: Sep 16, 2026Updated: Sep 18, 2026 Sources: CVE List NVDCWE-297
7.5HIGH
NVD MITRE
EPSS Score
0.4%
Top 69.9%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available
Self-Check
Not available

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.

No summary for this CVE yet.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:NI:HA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:HIntegrity
High
A:NAvailability
None
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Weaknesses

CWE-297

Affected Products

Apache Software Foundation
oss-project·USaka apache foundation
Apache ZooKeeperOn-premWeb App
Databases / cache-message-queue
apache
oss-project·USaka apache http server, apache httpd
zookeeperOn-premDatabase
Databases / cache-message-queue

Exploitability

Official Patch Available
Is your org exposed to CVE-2026-59969?Request an assessment to establish which checks are appropriate for your systems. Check my exposure

References

https://lists.apache.org/thread/qf9kwsgtgbgtvwls6f41281846xg0rss
lists.apache.org
http://www.openwall.com/lists/oss-security/2026/09/15/4
openwall.com

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