Vulnerability 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.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Apache | Zookeeper | >= 3.8.0, < 3.8.7 |
Related Weaknesses (CWE)
References
- https://lists.apache.org/thread/qf9kwsgtgbgtvwls6f41281846xg0rssMailing ListVendor Advisory
- http://www.openwall.com/lists/oss-security/2026/09/15/4Mailing ListThird Party Advisory
FAQ
What is CVE-2026-59969?
CVE-2026-59969 is a vulnerability with a CVSS score of 7.5 (HIGH). 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.cl...
How severe is CVE-2026-59969?
CVE-2026-59969 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-59969?
Check the references section above for vendor advisories and patch information. Affected products include: Apache Zookeeper.