Bazaar through 2.7.0, when Subprocess SSH is used, allows remote attackers
to execute arbitrary commands via a bzr+ssh URL with an initial dash
character in the hostname, a related issue to CVE-2017-9800,
CVE-2017-12836, CVE-2017-12976, CVE-2017-16228, CVE-2017-1000116, and
CVE-2017-1000117.

Adam Collard discovered that Bazaar did not properly handle host names
in 'bzr+ssh://' URLs. A remote attacker could use this to construct
a bazaar repository URL that when accessed could run arbitrary code
with the privileges of the user.