Bug 2535093 (CVE-2026-59739)

Summary: CVE-2026-59739 zookeeper: Apache ZooKeeper: Information disclosure via SetWatches reconnect replay
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: anujha, asoldano, asyoung, ataylor, bbaranow, bmaxwell, bstansbe, csuconic, dbruscin, dlofthou, eglynn, ehugonne, fmariani, fmongiar, gmalinko, gtully, istudens, ivassile, iweiss, janstey, jhollowa, jjoyce, jnethert, jpretori, jschluet, jsherman, jwon, kaycoth, kvanderr, lhh, mburns, mcarlett, mgarciac, mosmerov, msvehla, nwallace, pberan, pdelbell, pesilva, pjindal, pmackay, prichard, rgemmell, rgodfrey, rstancel, rstepani, sthirugn, tbish, tcunning, thjenkin, tlavocat, vdosoudi, yfang
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: ---
Doc Text:
A flaw was found in Apache ZooKeeper. This vulnerability allows a remote attacker to discover paths that should be restricted by Access Control Lists (ACLs). By registering watches on non-existent paths and then reconnecting after these paths are created with restricted ACLs, the attacker can bypass security checks. This information disclosure could expose sensitive path details, such as usernames or login identifiers.
 Story Points: ---
Clone Of: Environment:
Last Closed: Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 2542317, 2542318, 2542319    
Bug Blocks:    

Description OSIDB Bzimport 2026-09-16 09:46:04 UTC 
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.