CVE-2026-100300
Description
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).
Statement
Red Hat Product Security has determined that this vulnerability does not affect any currently supported Red Hat product. This assessment may evolve based on further analysis and discovery. For more information about this vulnerability and the products it affects, please see the linked references.
Mitigation
--- CME Mitigation Guidance (2026-11-06) ---
Disclaimer: The following mitigation solutions are provided as a courtesy, pending the application of an official patch. This content was generated utilizing AI tools in conjunction with data from https://cmetaxonomy.org. Customers are advised to independently evaluate and test these temporary mitigations within their own infrastructure.
The highest-value action is to restrict write permissions on the /zookeeper/quota subtree and block untrusted client traffic to ZooKeeper client ports: upgrade to Apache ZooKeeper 3.8.8 or 3.9.7, which handle exceptions properly during quota-node data parsing and application to prevent crashing the request-processing thread, closing writing crafted quota-node data or paths to the /zookeeper/quota subtree. Until patched, this is a concern on deployments exposing the ZooKeeper client port with default world-writable permissions on /zookeeper/quota, so restrict network access to the ZooKeeper client port and remove world-writable permissions from the /zookeeper/quota subtree. These controls limit blast radius and contain exploitation, but they do not fix the underlying improper exception handling defect — apply the upstream patch to fully remediate.
Understanding the Weakness (CWE)
Availability,Confidentiality
Technical Impact: DoS: Crash, Exit, or Restart; Read Application Data
An uncaught exception could cause the system to be placed in a state that could lead to a crash, exposure of sensitive information, or other unintended behaviors.
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