1) consider installing the "unattended-upgrades" tool, to install security updates via cron. https://help.ubuntu.com/community/AutomaticSecurityUpdates
2) specific Ubuntu Security Notice on GnuTLS: http://www.ubuntu.com/usn/usn-2121-1/
3) List specific package affected:
dpkg-query -W libgnutls*
libgnutls-openssl27:amd64 2.12.23-1ubuntu4 libgnutls26:amd64 2.12.23-1ubuntu4
I'm on Linux Mint, and the above seem to show that I'm protected. Yay!
.../ubuntu/+source/gnutls26/2.12.23-1ubuntu4.2
Yours is:
.../ubuntu/+source/gnutls26/2.12.23-1ubuntu4
See:
https://launchpad.net/ubuntu/+source/gnutls26/2.12.23-1ubunt...