---
id: CVE-2026-59739
title: "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…"
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…"
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N'
cwe:
  - CWE-862
vendor: apache
product: zookeeper
affected:
  - 'zookeeper >= 3.8.0, < 3.8.7'
  - 'zookeeper >= 3.9.0, < 3.9.6'
patched:
  - zookeeper 3.9.6
published: '2026-09-16'
updated: '2026-09-18'
sourceUpdated: '2026-09-18T14:37:10.223'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-59739'
references:
  - url: 'https://lists.apache.org/thread/v0lrwsbdxvx6w67p3z7fxf3hzyncq55l'
    label: security@apache.org
tags:
  - nvd
  - cve.org
epss: 0.00568
epssPercentile: 0.45576
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-09-17T19:17:33.790349Z'
ingestedAt: '2026-09-16T09:53:11.603Z'
---

## Overview

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.

## Affected

- `zookeeper >= 3.8.0, < 3.8.7`
- `zookeeper >= 3.9.0, < 3.9.6`

## Remediation

Upgrade past the affected range:

- `zookeeper 3.9.6`