CVE-2026-59739

Apache ZooKeeper: Information disclosure via SetWatches reconnect replay

State: Published
Severity: 7.5 High
Published: Sep 16, 2026
Updated: Sep 17, 2026
Reserved: Jul 6, 2026

Description

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.

Scores

CVSS	Score	Vector	Source
3.1	7.5 High	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N	CISA-ADP

Weaknesses

CWE-862 Missing Authorization

Affected Products

Product	Versions
Apache ZooKeeperApache Software Foundation	3.9.0 through 3.9.5Affected 3.8.0 through 3.8.6Affected

References

https://lists.apache.org/thread/v0lrwsbdxvx6w67p3z7fxf3hzyncq55lvendor-advisory

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