UBUNTU-CVE-2026-100252

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UBUNTU-CVE-2026-100252

Summary:

Details: 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.

References: https://ubuntu.com/security/CVE-2026-100252, https://www.cve.org/CVERecord?id=CVE-2026-100252, https://lists.apache.org/thread.html/81rdyqlmlp3dtkkqgp8t5080g3b9r2pj, http://www.openwall.com/lists/oss-security/2026/11/03/10