---
id: CVE-2026-100252
title: >-
  Apache ZooKeeper: SASL authorization bypass on the client port through a
  client-supplied authorization ID
summary: >-
  Improper Authorization vulnerability in Apache ZooKeeper.


  When SASL authentication is enabled on the client port, the server's SASL
  callback handler grants every authorization identity (authzid) that a client
  requests, without checking …
severity: high
cvss: 8.6
cvssVector: 'CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N'
cvssSource: cna
cwe:
  - CWE-863
vendor: Apache Software Foundation
product: 'org.apache.zookeeper:zookeeper'
affected:
  - 'org.apache.zookeeper:zookeeper >= 3.9.0 <= 3.9.6'
  - 'org.apache.zookeeper:zookeeper >= 3.8.0 <= 3.8.7'
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-11-04T00:00:00+00:00'
published: '2026-11-04'
updated: '2026-11-05'
sourceUpdated: '2026-11-05T04:55:52.687Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-100252'
references:
  - url: 'https://lists.apache.org/thread.html/81rdyqlmlp3dtkkqgp8t5080g3b9r2pj'
tags:
  - cve.org
ingestedAt: '2026-11-05T21:36:00.736Z'
---

## Overview

Improper Authorization vulnerability in Apache ZooKeeper.

When SASL authentication is enabled on the client port, the server's SASL callback handler grants every authorization identity (authzid) that a client requests, without checking it against the principal the client authenticated as. The server then tries to replace the requested identity with a canonical form of the authenticated principal, derived from the zookeeper.security.auth_to_local rules. If no rule applies to the principal, canonicalization fails and the error is only logged. The client-requested authzid then becomes the session's SASL identity for all ACL checks.

An authenticated client whose principal is not covered by the auth_to_local rules can therefore claim any SASL identity. With the default rules, this includes any Kerberos principal from a realm other than the server's default realm, such as a principal from a cross-realm trusted realm. The client then gets the permissions granted to that identity in sasl ACLs. If the requested identity matches a configured zookeeper.superUser, it gets superuser access to the whole data tree.

Users are recommended to upgrade to version 3.8.8 or 3.9.7, which fixes the issue.

## Affected

- `org.apache.zookeeper:zookeeper >= 3.9.0 <= 3.9.6`
- `org.apache.zookeeper:zookeeper >= 3.8.0 <= 3.8.7`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.