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CVE-2016-5017: Buffer overflow vulnerability in ZooKeeper C cli shell

Severity: moderate

Vendor:
The Apache Software Foundation

Versions Affected:
ZooKeeper 3.4.0 to 3.4.8
ZooKeeper 3.5.0 to 3.5.2
The unsupported ZooKeeper 1.x through 3.3.x versions may be also affected

Note: The 3.5 branch is still alpha at this time.

Description:
The ZooKeeper C client shells "cli_st" and "cli_mt" have a buffer
overflow vulnerability associated with parsing of the input command
when using the "cmd:<cmd>" batch mode syntax. If the command string
exceeds 1024 characters a buffer overflow will occur. There is no
known compromise which takes advantage of this vulnerability, and if
security is enabled the attacker would be limited by client level
security constraints. The C cli shell is intended as a sample/example
of how to use the C client interface, not as a production tool - the
documentation has also been clarified on this point.

Mitigation:
It is important to use the fully featured/supported Java cli shell rather
than the C cli shell independent of version.

- ZooKeeper 3.4.x users should upgrade to 3.4.9 or apply this patch:
https://git-wip-us.apache.org/repos/asf?p=zookeeper.git;a=commitdiff;h=27ecf981a15554dc8e64a28630af7a5c9e2bdf4f

- ZooKeeper 3.5.x users should upgrade to 3.5.3 when released or apply
this patch:
https://git-wip-us.apache.org/repos/asf?p=zookeeper.git;a=commitdiff;h=f09154d6648eeb4ec5e1ac8a2bacbd2f8c87c14a

The patch solves the problem reported here, but it does not make the
client ready for production use. The community has no plan to make
this client production ready at this time, and strongly recommends that
users move to the Java cli and use the C cli for illustration purposes only.


Credit:
This issue was discovered by Lyon Yang, an Apple security researcher.

References:
https://zookeeper.apache.org/security.html
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