gui2/viewer/bookmarkmanager.py in Calibre 3.18 calls cPickle.load on imported bookmark data, which allows remote attackers to execute arbitrary code via a crafted .pickle file, as demonstrated by Python code that contains an os.system call.
Created calibre tracking bugs for this issue:
Affects: fedora-all [bug 1553919]
The upstream patch mentioned in the original post was from a little over a year ago now. There's been several Calibre releases since then, so it's been fixed for a while, right? Can we close this issue?