Epoxy can cure in a vacuum, as demonstrated by common fabrication procedures (sort of). The temperature isn't actually that big of a thing. Space is "cold" because there's no heat but also nothing to conduct it away. It actually gets quite hot if you're facing the sun as well. Long story short though, as long as there's no gas passing through the hole, it should stay around the internal temperature of the ISS or at least close enough to cure.