October 27, 2026

CVE Watchtower

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CVE-2026-59739NVD

Vulnerability Summary

Information disclosure via SetWatches reconnect replay in Apache ZooKeeper due to missing ACL check. An attacker can discover ACL-restricted paths by registering exists-watches on non-existent paths, then reconnecting after the paths are created with restricted ACLs. Issue is caused by incomplete fix for CVE-2024-23944 (ZOOKEEPER-4799). The fix added ACL checking to WatchManager.triggerWatch(). However, DataTree.setWatches() — the SetWatches/SetWatches2 reconnect replay handler — still calls watcher.process(event) with null ACL, bypassing the check entirely. It's important to note that only the path is exposed by this vulnerability, not the data of znode, but since znode path can contain sensitive information like user name or login ID, this issue is potentially critical.

Users are recommended to upgrade to version 3.9.6, 3.8.7 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)
0.55%Probability
Root Weakness (CWE)
CWE-862: Missing Authorization ↗
The software does not perform an authorization check when an actor attempts to access a resource or perform an action.

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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📈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.
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External References