CVE-2026-59739
Apache ZooKeeper: Information disclosure via SetWatches reconnect replay
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.
INFO
Published Date :
Sept. 16, 2026, 10:16 a.m.
Last Modified :
Sept. 18, 2026, 2:37 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | 134c704f-9b21-4f2e-91b3-4a467353bcc0 |
Solution
- Upgrade to ZooKeeper version 3.9.6 or 3.8.7.
- Ensure ACL checks are enforced during SetWatches reconnect.
- Monitor system for unauthorized path discovery.
- Review access controls for sensitive paths.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-59739.
| URL | Resource |
|---|---|
| https://lists.apache.org/thread/v0lrwsbdxvx6w67p3z7fxf3hzyncq55l | Mailing List Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-59739 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-59739
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-59739 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-59739 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Sep. 18, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:a:apache:zookeeper:*:*:*:*:*:*:*:* versions from (including) 3.8.0 up to (excluding) 3.8.7 *cpe:2.3:a:apache:zookeeper:*:*:*:*:*:*:*:* versions from (including) 3.9.0 up to (excluding) 3.9.6 Added Reference Type Apache Software Foundation: https://lists.apache.org/thread/v0lrwsbdxvx6w67p3z7fxf3hzyncq55l Types: Mailing List, Vendor Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Sep. 17, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N Added SSVC {'id': 'CVE-2026-59739', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'yes'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-09-17T19:17:33.790349Z'} -
New CVE Received by [email protected]
Sep. 16, 2026
Action Type Old Value New Value Added 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. Added CWE CWE-862 Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/59xxx/CVE-2026-59739.json">CVE-2026-59739</a> Added Reference https://lists.apache.org/thread/v0lrwsbdxvx6w67p3z7fxf3hzyncq55l