GnuTLS incorrectly validates the first byte of padding in CBC modes
https://security-tracker.debian.org/tracker/CVE-2015-8313
https://bugzilla.suse.com/show_bug.cgi?id=CVE-2015-8313
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2015-8313
https://blog.hboeck.de/archives/877-A-little-POODLE-left-in-GnuTLS-old-versions.html
http://www.securityfocus.com/bid/78327
http://www.securityfocus.com/archive/1/537012/100/0/threaded