The stable up-to-date version of Epiphany browser at the moment of this post is 3.18.5. As I have some problem with bookmarks in it I was wandering whether some later version could be used in Loki... or not...
the Gnome team has recommended elementary upgrade to 3.18.8. So far, no update.
Try running synaptic package manager and check for newer versions. Though these will not have the elementary visual integration.