file_copy_fallback in gio/gfile.c in GNOME GLib 2.15.0 through 2.61.1 does not properly restrict file permissions while a copy operation is in progress. Instead, default permissions are used.
https://usn.ubuntu.com/4014-2/
https://usn.ubuntu.com/4014-1/
https://security.netapp.com/advisory/ntap-20190606-0003/
https://lists.debian.org/debian-lts-announce/2019/06/msg00013.html
https://gitlab.gnome.org/GNOME/glib/commit/d8f8f4d637ce43f8699ba94c9b7648beda0ca174
https://access.redhat.com/errata/RHSA-2019:3530
http://lists.opensuse.org/opensuse-security-announce/2019-06/msg00076.html