CVE-2026-59969

highpriority · track · 0EPSS 0.003 · 26 %ileUS

grimoire priorityP2 · Scheduled

Exploitable?

—

no known exploitation

Likely / severe?

0.33% (26th) EPSS

CVSS 7.5 · high

Is it mine?

4 products

Check your exposure

Who says so?

2 sources

nvd · osv

EPSS · scored 2026-10-27

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.

cvss

Technical severity, 0–10. One row per scoring source.

7.5

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 6.9–7.5

v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:Nsecondaryexploitability 3.9 · impact 3.6

v3.16.9mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N/E:Usecondary · CVSS-BT (t0sche)

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: none · Automatable: yes · Technical Impact: partialcoordinatorcisa_ssvcUS

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-297US

affected products (4)

Products and version ranges known to be affected.

apache zookeeper3.8.0 → 3.8.7nvdUScpe:2.3:a:apache:zookeeper:*:*:*:*:*:*:*:*
apache zookeeper3.9.0 → 3.9.6nvdUScpe:2.3:a:apache:zookeeper:*:*:*:*:*:*:*:*
Bitnami zookeeper3.8.0 → 3.8.7osvUSpkg:bitnami/zookeeper
Bitnami zookeeper3.9.0 → 3.9.6osvUSpkg:bitnami/zookeeper

advisories (1)

Vendor and ecosystem advisories describing this.

BIT-zookeeper-2026-59969Apache ZooKeeper: Improper validation of certificate with host mismatch in FIPS mode2026-09-19vendor · osvUS
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.

sources

Which sources assert this record, and when.

nvd osv NVD CVE.org MITRE

published 2026-09-16modified 2026-09-18

references (2) nvd

External citations — patches, advisories, analysis.

http://www.openwall.com/lists/oss-security/2026/09/15/4Mailing ListThird Party Advisory
https://lists.apache.org/thread/qf9kwsgtgbgtvwls6f41281846xg0rssMailing ListVendor Advisory

scry

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