Description
Incorrect authorization due to a time-of-check to time-of-use (TOCTOU) race condition in the setACL request handling of Apache ZooKeeper.

When a node's ACL is changed via setACL, the pending change is not published to the server's outstanding change record for that node. Any request that is prepared (and authorized) after the setACL is submitted but before it commits is therefore checked against the previous, pre-revocation ACL, yet is applied to the data tree after the ACL change has taken effect. A client that currently holds a permission can use this window to perform operations requiring that permission through and after its revocation — for example, committing writes or deletes after losing write access, or re-granting itself full permissions, which persistently defeats the revocation. In deployments transitioning from the default OPEN_ACL_UNSAFE ACL to a restrictive ACL, any unauthenticated client can exploit this during the transition.

This issue affects Apache ZooKeeper up to and including 3.9.6. Users are recommended to upgrade to version 3.8.8 or 3.9.7, which fixes the issue.
Published: 2026-11-04
Score: 6 Medium
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
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Remediation

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History

Wed, 04 Nov 2026 13:00:00 +0000

Type Values Removed Values Added
First Time appeared Apache
Apache zookeeper
Vendors & Products Apache
Apache zookeeper

Wed, 04 Nov 2026 12:30:00 +0000

Type Values Removed Values Added
References

Wed, 04 Nov 2026 11:00:00 +0000

Type Values Removed Values Added
Description Incorrect authorization due to a time-of-check to time-of-use (TOCTOU) race condition in the setACL request handling of Apache ZooKeeper. When a node's ACL is changed via setACL, the pending change is not published to the server's outstanding change record for that node. Any request that is prepared (and authorized) after the setACL is submitted but before it commits is therefore checked against the previous, pre-revocation ACL, yet is applied to the data tree after the ACL change has taken effect. A client that currently holds a permission can use this window to perform operations requiring that permission through and after its revocation — for example, committing writes or deletes after losing write access, or re-granting itself full permissions, which persistently defeats the revocation. In deployments transitioning from the default OPEN_ACL_UNSAFE ACL to a restrictive ACL, any unauthenticated client can exploit this during the transition. This issue affects Apache ZooKeeper up to and including 3.9.6. Users are recommended to upgrade to version 3.8.8 or 3.9.7, which fixes the issue.
Title Apache ZooKeeper: ACL enforcement bypass allows unauthorized operations to commit after an ACL revocation
Weaknesses CWE-367
References
Metrics cvssV4_0

{'score': 6, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N'}


Subscriptions

Apache Zookeeper
cve-icon MITRE

Status: PUBLISHED

Assigner: apache

Published:

Updated: 2026-11-04T11:09:04.801Z

Reserved: 2026-09-25T15:55:12.809Z

Link: CVE-2026-100235

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-11-04T11:17:04.960

Modified: 2026-11-04T14:10:09.713

Link: CVE-2026-100235

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-11-04T12:45:13Z

Weaknesses