Debian: DSA-4214-1 Moderate: Zookeeper Access Control Flaw

It was discovered that Zookeeper, a service for maintaining configuration
information, enforced no authentication/authorisation when a server
attempts to join a Zookeeper quorum.

This update backports authentication support. Additional configuration
steps are needed, please see
https://cwiki.apache.org/confluence/display/ZOOKEEPER/Server-Server+mutual+authentication
for additional information.

For the oldstable distribution (jessie), this problem has been fixed
in version 3.4.9-3+deb8u1.

For the stable distribution (stretch), this problem has been fixed in
version 3.4.9-3+deb9u1.

We recommend that you upgrade your zookeeper packages.

For the detailed security status of zookeeper please refer to
its security tracker page at:
https://security-tracker.debian.org/tracker/source-package/zookeeper

Further information about Debian Security Advisories, how to apply
these updates to your system and frequently asked questions can be
found at: https://www.debian.org/security/