The FTP backend for Duplicity before 0.4.9 sends the password as a command line argument when calling ncftp, which might allow local users to read the password by listing the process and its arguments.
bugs.debian.org/cgi-bin/bugreport.cgi?bug=442840
duplicity.nongnu.org/CHANGELOG
osvdb.org/42339
secunia.com/advisories/28917
www.securityfocus.com/bid/27771
bugzilla.redhat.com/show_bug.cgi?id=293081
www.redhat.com/archives/fedora-package-announce/2008-February/msg00356.html
www.redhat.com/archives/fedora-package-announce/2008-February/msg00445.html