CVE-2026-59969High· 7.5▾ TwilightApache 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 ena…
▾ Twilight zone — High severity, or a signal on a lesser flaw
impact 41.3 · likelihood 0.1 · exploitation 0
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Stakeholder-Specific Vulnerability Categorization from CISA's ADP record at CVE.org: whether exploitation is observed, whether an attack can be automated, and how much of the system is at stake.
Exploit-prediction probability, daily snapshots since Sep 17.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via NVD
0.1%
— → 7.5
none → high
Last analysed / modified upstream
0.1% → 0.4%
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.
zookeeper >= 3.8.0, < 3.8.7zookeeper >= 3.9.0, < 3.9.6Upgrade past the affected range:
zookeeper 3.9.6Field changes observed since this record was first indexed.
Connected by shared product, vendor, weakness, or advisory.
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