October 27, 2026

CVE Watchtower

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CVE-2026-59969NVD

Vulnerability 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.
Severity Level
UNKNOWN
Published Date
Sep 16, 2026
Last Modified
Sep 17, 2026
Exploitation Status
No confirmed exploitation yet
EPSS Score (30-Day)
0.33%Probability
Root Weakness (CWE)
CWE-297: Unknown/Unlisted Weakness ↗
Refer to the official MITRE database for detailed architectural specifications regarding this weakness.

Affected & Patched Versions

Affected Versions
  • Apache Software Foundation Apache ZooKeeper >= 3.9.0 and <= 3.9.5
  • Apache Software Foundation Apache ZooKeeper >= 3.8.0 and <= 3.8.6
Patched Versions
  • Apache Software Foundation Apache ZooKeeper 3.9.5
  • Apache Software Foundation Apache ZooKeeper 3.8.6
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🎁7-Day Free Trial — Try Pro or Team, no card required.
📧Email Delivery — Threat intel straight to your inbox.
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🚨All New CVEs — Be the first to know.
📈EPSS Spike Alerts — Catch rising risk before it peaks.
🎯Custom EPSS/CVSS — Filter noise, focus on risk.
🛡️Exploit Intel — A 2nd confirmed-exploit signal beyond KEV.
🐙GitHub Issues — Auto-tracked, no duplicates.
📬Weekly Digest — One clean summary, not inbox spam.
🏷️Watchlist Groups — Tag alerts by team (Infra/AppSec/SOC).
💬Webhooks — Slack & Teams integration.
🔀Smart Routing — Critical alerts to one channel, rest to another.
🚫Ad-Free — Uninterrupted experience.

External References