# CVE-2026-100252: Apache ZooKeeper: SASL authorization bypass on the client port through a client-supplied authorization ID

Status: published. Published: 2026-11-04. Updated: 2026-11-04.

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.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- Apache Software Foundation / Apache ZooKeeper (org.apache.zookeeper:zookeeper): ≥ 3.9.0; ≤ 3.9.6 (affected, maven); ≥ 3.8.0; ≤ 3.8.7 (affected, maven). Source: CNA: apache

## Severity and prioritization

- CVSS 4.0: 8.6 (high); 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; source: CNA: apache

- CVSS 4.0: 8.6 (high); 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/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; source: NVD: security@apache.org

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-863

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://lists.apache.org/thread.html/81rdyqlmlp3dtkkqgp8t5080g3b9r2pj (CNA: apache; vendor-advisory)

- http://www.openwall.com/lists/oss-security/2026/11/03/10 (ADP: CVE)

- https://lists.apache.org/thread.html/81rdyqlmlp3dtkkqgp8t5080g3b9r2pj (security@apache.org)

## Provenance

- CNA: apache: https://www.cve.org/CVERecord?id=CVE-2026-100252; retrieved 2026-11-04; source updated 2026-11-04

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-100252; retrieved 2026-11-04; source updated 2026-11-04

Revision: 00a16e66331aaa1530ba97a0fb9c1f316f25c4cf746acb6c5dbc8ef8eb44ff1b

Canonical: https://y2.dev/cve/CVE-2026-100252

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