The current version avilable for FreeBSD is end-of-life since 01.12.2016 and has already been updated upstream.
See here: http://www.varnish-cache.org/releases/rel4.1.5.html#rel4-1-5
Release overview: http://www.varnish-cache.org/releases/index.html
Available version @ ports: 4.1.3
Latest version @ upstream: 4.1.5
Thanks for taking a look at it.
A commit references this bug:
Date: Tue Mar 21 13:33:24 UTC 2017
New revision: 436604
www/varnish4: Update to 4.1.5