Description
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.
Published: 2026-11-04
Score: 8.6 High
EPSS: n/a
KEV: No
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History

Wed, 04 Nov 2026 13:00:00 +0000

Type Values Removed Values Added
First Time appeared Apache
Apache zookeeper
Vendors & Products Apache
Apache zookeeper

Wed, 04 Nov 2026 12:30:00 +0000

Type Values Removed Values Added
References

Wed, 04 Nov 2026 11:00:00 +0000

Type Values Removed Values Added
Description 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.
Title Apache ZooKeeper: SASL authorization bypass on the client port through a client-supplied authorization ID
Weaknesses CWE-863
References
Metrics cvssV4_0

{'score': 8.6, 'vector': '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'}


Subscriptions

Apache Zookeeper
cve-icon MITRE

Status: PUBLISHED

Assigner: apache

Published:

Updated: 2026-11-04T11:09:10.129Z

Reserved: 2026-09-25T16:45:48.869Z

Link: CVE-2026-100252

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-11-04T11:17:06.717

Modified: 2026-11-04T14:10:09.713

Link: CVE-2026-100252

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-11-04T12:45:13Z

Weaknesses