Answer in brief
CVE-2026-100235 records a Medium severity (CVSS 6.0) vulnerability in Apache ZooKeeper: ACL enforcement bypass allows unauthorized operations to commit after an ACL revocation. The current sources do not mark it as known exploited. The current feed maps Apache Software Foundation/org.apache.zookeeper:zookeeper (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 6.0. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Apache Software Foundation/org.apache.zookeeper:zookeeper (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Apache Software Foundation/org.apache.zookeeper:zookeepergeneric | >=3.9.0 <=3.9.6 || >=3.8.0 <=3.8.7 | Not reported |
Published upstream
Nov 4, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Nov 4, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Nov 4, 2026
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.
Quoted source text, attributed separately from HOL analysis.