OCTOBER 13, 2026
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Case File

CVE-2026-59739

HIGH · CVSS 7.5 EPSS 0.55%

Source: NVD + CISA KEV + EPSS · Published 2026-09-16 · Last synced 2026-10-13

CyberRota Analysis

AI-Generated

Apache ZooKeeper is vulnerable to information disclosure due to a missing ACL check in the SetWatches reconnect replay mechanism, allowing attackers to identify ACL-restricted paths by exploiting the system's watch functionality. While the actual data within the znode remains protected, the exposure of sensitive path information, such as usernames or login IDs, poses a significant risk. Organizations using affected versions should prioritize upgrading to versions 3.9.6 or 3.8.7 to mitigate this vulnerability.

CVE
CVE-2026-59739
Severity
HIGH
CVSS
7.5
EPSS
0.55%
Apache

Original NVD 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.

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