The mount target path check in mounter.cpp 'mpOk()' is insufficient. A regular user can this way mount a CIFS filesystem anywhere, and not just beneath /home by passing relative path components (CVE-2018-12559).
Arbitrary unmounts can be performed by regular users the same way (CVE-2018-12560).
A regular user can inject additional mount options like file_mode= by manipulating e.g. the domain parameter of the samba URL (CVE-2018-12561).
The wrapper script 'mount.cifs.wrapper' uses the shell to forward the arguments to the actual mount.cifs binary. The shell evaluates wildcards which can also be injected (CVE-2018-12562).
To fix these issues, the vulnerable D-Bus service has been removed.