Get your hands on a syringe and some good wood glue, the yellow carpenters glue is what I use, (titebond)
You want to get enough glue in there than when you clamp it, the glue squeezes out. Another trick I've used if no syringe is available or if the crack is to small to fit a needle into, is to thin some of the glue, put it into a plastic baggie, let it all sit in one corner, then cut the opposite corner off, slide the baggie into the crack and squeeze the glue out of the cut corner into the crack.
Clamp it tight and let it dry. You should be fine, wipe away the excess glue while it's wet and you won't have to do anything else. Chances are good you won't even need to dress any of the frets if it didn't buzz before the crack started.