Bug 2566837 (CVE-2026-100300)

Summary: CVE-2026-100300 zookeeper: zookeeper: Denial of Service via improper exception handling in quota subsystem
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: high    
Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in Apache ZooKeeper. An unauthenticated remote attacker can exploit improper handling of exceptions in the quota subsystem by writing to the default world-writable quota directory. This action crashes the primary request-processing thread and renders the on-disk data unbootable, resulting in a persistent Denial of Service (DoS).
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Description OSIDB Bzimport 2026-11-04 10:58:09 UTC
Improper handling of exceptional conditions in the quota subsystem of Apache ZooKeeper allows an attacker able to write under the /zookeeper/quota subtree — unauthenticated on default deployments, where that subtree is world-writable — to crash the server's critical request-processing thread and render the on-disk data directory permanently unbootable.

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.