Security updates for Thursday

Security updates have been issued by Debian (xorg-server), Fedora (kernel), openSUSE (clamav, fluidsynth, python-bleach, spamassassin, and xorg-x11-server), Red Hat (gnutls and nettle, libldb, and thunderbird), Scientific Linux (thunderbird), SUSE (clamav, util-linux, and xorg-x11-server), and Ubuntu (network-manager and underscore).