CVE-2026-59739: CWE-862 Missing Authorization in Apache Software Foundation Apache ZooKeeper
CVE-2026-59739 is a missing authorization vulnerability in Apache ZooKeeper that allows information disclosure of ACL-restricted paths. An attacker can register watches on non-existent paths and, upon reconnecting after those paths are created with restricted ACLs, discover the existence of these paths. The vulnerability arises from an incomplete fix for a previous issue, where the ACL check was not enforced during the SetWatches reconnect replay. Although the data within the znode is not exposed, the path itself may contain sensitive information such as usernames or login IDs. The issue affects Apache ZooKeeper versions 3.8.0 through 3.8.6 and 3.9.0 through 3.9.5. Upgrading to versions 3.8.7 or 3.9.6 addresses the vulnerability.
AI Analysis
Technical Summary
This vulnerability in Apache ZooKeeper is due to missing authorization checks during the SetWatches reconnect replay process. Specifically, while ACL checks were added to WatchManager.triggerWatch(), the DataTree.setWatches() method still calls watcher.process(event) with a null ACL, bypassing authorization. This allows an attacker to discover ACL-restricted paths by registering exists-watches on non-existent paths and reconnecting after those paths are created with restricted ACLs. The flaw does not expose znode data but reveals path names, which may contain sensitive information. The issue is a regression from an incomplete fix for CVE-2024-23944 (ZOOKEEPER-4799).
Potential Impact
The vulnerability enables an attacker to infer the existence of ACL-restricted paths in ZooKeeper by exploiting missing authorization checks during watch replay. While the actual data of the znodes is not disclosed, the exposure of path names can lead to sensitive information leakage, such as user names or login IDs embedded in paths. This information disclosure could aid attackers in reconnaissance and further attacks.
Mitigation Recommendations
Users should upgrade Apache ZooKeeper to version 3.9.6 or 3.8.7, where this vulnerability has been fixed. No other mitigations are indicated. Patch status is confirmed by the vendor advisory recommending these versions.
CVE-2026-59739: CWE-862 Missing Authorization in Apache Software Foundation Apache ZooKeeper
Description
CVE-2026-59739 is a missing authorization vulnerability in Apache ZooKeeper that allows information disclosure of ACL-restricted paths. An attacker can register watches on non-existent paths and, upon reconnecting after those paths are created with restricted ACLs, discover the existence of these paths. The vulnerability arises from an incomplete fix for a previous issue, where the ACL check was not enforced during the SetWatches reconnect replay. Although the data within the znode is not exposed, the path itself may contain sensitive information such as usernames or login IDs. The issue affects Apache ZooKeeper versions 3.8.0 through 3.8.6 and 3.9.0 through 3.9.5. Upgrading to versions 3.8.7 or 3.9.6 addresses the vulnerability.
Affected software
Apache Software Foundation
Apache ZooKeeper
pkg:maven/Apache Software Foundation/org.apache.zookeeper:zookeeperRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability in Apache ZooKeeper is due to missing authorization checks during the SetWatches reconnect replay process. Specifically, while ACL checks were added to WatchManager.triggerWatch(), the DataTree.setWatches() method still calls watcher.process(event) with a null ACL, bypassing authorization. This allows an attacker to discover ACL-restricted paths by registering exists-watches on non-existent paths and reconnecting after those paths are created with restricted ACLs. The flaw does not expose znode data but reveals path names, which may contain sensitive information. The issue is a regression from an incomplete fix for CVE-2024-23944 (ZOOKEEPER-4799).
Potential Impact
The vulnerability enables an attacker to infer the existence of ACL-restricted paths in ZooKeeper by exploiting missing authorization checks during watch replay. While the actual data of the znodes is not disclosed, the exposure of path names can lead to sensitive information leakage, such as user names or login IDs embedded in paths. This information disclosure could aid attackers in reconnaissance and further attacks.
Mitigation Recommendations
Users should upgrade Apache ZooKeeper to version 3.9.6 or 3.8.7, where this vulnerability has been fixed. No other mitigations are indicated. Patch status is confirmed by the vendor advisory recommending these versions.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- apache
- Date Reserved
- 2026-07-06T20:46:19.936Z
- State
- PUBLISHED
Threat ID: 6aaa659d55bf5e2cf5501be9
Added to database: 09/16/2026, 09:47:09 UTC
Last enriched: 09/16/2026, 10:01:49 UTC
Last updated: 09/16/2026, 10:08:54 UTC
Views: 5
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