And you are right to be concerned. A kernel contributor already demonstrated
this by creating a "snaps" package that can steal data from X11 sessions...
http://news.softpedia.com/news/developer-claims-that-canonical-s-new-snap-format-isn-t-secure-on-ubuntu-desktop-503287.shtml
"According to Matthew Garrett, a renowned CoreOS security developer and Linux
kernel contributor, Canonical's new snap package format is not secure at all
when it is used under X.Org Server (X Window System), which, for now, is
still the default display server of the Ubuntu 16.04 LTS (Xenial Xerus)
operating system."
