Severity: important
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
Affected versions:
- Apache ZooKeeper 3.9.0 through 3.9.6
- Apache ZooKeeper 3.8.0 through 3.8.7
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.
Credit:
cunyi li <[email protected]> (reporter)
Prasath Jayasundar & PayPal Cyber Security Team (reporter)
References:
https://zookeeper.apache.org/
https://www.cve.org/CVERecord?id=CVE-2026-100252
