Security updates for Tuesday

Security updates have been issued by Debian (xen), Fedora (clamav, community-mysql, dnsmasq, flatpak, libtasn1, mupdf, p7zip, rsync, squid, thunderbird, tomcat, unbound, and zziplib), Mageia (clamav, curl, dovecot, ffmpeg, gcab, kernel, libtiff, libvpx, php-smarty, pure-ftpd, redis, and thunderbird), openSUSE (apache-commons-email), Red Hat (rh-mariadb100-mariadb), SUSE (firefox), and Ubuntu (clamav, squid3, and systemd).