CVE-2026-100235
Apache ZooKeeper: ACL enforcement bypass allows unauthorized operations to commit after an ACL revocation
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.
INFO
Published Date :
Nov. 4, 2026, 11:17 a.m.
Last Modified :
Nov. 4, 2026, 11:17 a.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 4.0 | MEDIUM | f0158376-9dc2-43b6-827c-5f631a4d8d09 | ||||
| CVSS 4.0 | MEDIUM | [email protected] |
Solution
- Upgrade Apache ZooKeeper to version 3.8.8 or later.
- Upgrade Apache ZooKeeper to version 3.9.7 or later.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-100235.
| URL | Resource |
|---|---|
| https://lists.apache.org/thread.html/r40gp594o64mycwybc3v9dtvrm0vos0l |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-100235 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-100235
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-100235 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-100235 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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New CVE Received by [email protected]
Nov. 04, 2026
Action Type Old Value New Value 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. Added CVSS V4.0 AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CWE CWE-367 Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/100xxx/CVE-2026-100235.json">CVE-2026-100235</a> Added Reference https://lists.apache.org/thread.html/r40gp594o64mycwybc3v9dtvrm0vos0l