Advisory severityHigh7.5Apache Software Foundation

High [CVE-2026-59969] Apache ZooKeeper quorum TLS fails to enforce peer hostname verification in FIPS-mode deployments

This high-severity Apache Software Foundation advisory covers CVE-2026-59969; related products: Apache ZooKeeper.

Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.

CVE-2026-59969 Source published Sep 16, 2026Source updated Sep 18, 2026

VulniPulse record published Sep 16, 2026Record updated Sep 18, 2026

CVE-2026-59969

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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.

Affected versions

Apache ZooKeeper 3.9.0 through 3.9.5
Apache ZooKeeper 3.8.0 through 3.8.6

Official advisory · high-confidence parse· fetched 20 days ago·verify at source

Fixed versions

3.8.7
3.9.6

Official advisory · high-confidence parse· fetched 20 days ago·verify at source

Mitigation checklist

Recommended fix / mitigation

Users are recommended to upgrade to version 3.8.7 or 3.9.6, which fixes the issue.

Official advisory · high-confidence parse· fetched 20 days ago·verify at source

Sources

Official and corroborating records used to build this advisory.

Official vendor advisoryofficial
Official advisory page fetched and parsed; accepted detail fields are attributed to this page.
Apache Software Foundation
CVE.org CNA recordCVE.org
Independent CNA record used for near-real-time discovery and missed-CVE reconciliation. Discovered from the machine-readable feed https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/delta.json; this link opens the CVE.org record for CVE-2026-59969 instead of the raw feed document.
CVE Program

Cross-references

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CVE-2026-59969NVD CVE.org MITRE

Official resources

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