The _mediaLibraryPlayCb function in mainwindow.py in pitivi before 0.95 allows attackers to execute arbitrary code via shell metacharacters in a file path.
https://git.gnome.org/browse/pitivi/commit/?id=45a4c84edb3b4343f199bba1c65502e3f49f5bb2
https://bugs.launchpad.net/ubuntu/+source/pitivi/+bug/1495272