Debian: DSA-3871-1 Critical: Zookeeper CPU Consumption DoS Risk

It was discovered that Zookeeper, a service for maintaining
configuration information, didn't restrict access to the computationally
expensive wchp/wchc commands which could result in denial of service by
elevated CPU consumption.

This update disables those two commands by default. The new
configuration option "4lw.commands.whitelist" can be used to whitelist
commands selectively (and the full set of commands can be restored
with '*')

For the stable distribution (jessie), this problem has been fixed in
version 3.4.5+dfsg-2+deb8u2.

For the unstable distribution (sid), this problem will be fixed soon.

We recommend that you upgrade your zookeeper packages.

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/