The recent addition of nbd+ssh:// URIs to have libnbd initiate a connection to an NBD server via an ssh process did not sanitize the hostname of the ssh server. If a malicious actor can convince libnbd to open an arbitrary URI, use of non-standard hostnames beginning with '-o' would be treated as arguments to the ssh process rather than a hostname, which in turn could trigger execution of arbitrary processes under the privilege of the user running libnbd.