Recently I noticed that this was happening around our shower:
See that crack around the top edge? Prime place for moisture to enter the walls and start a lovely mold problem, especially because the fan is currently non-operational. Yikes! I am surprised and also not at all surprised that I didn't notice it sooner =).
The temporary fix is easy enough, if a little messy. I scrubbed around the shower and scraped off the old caulking, then re-applied silicone caulk around the edge.
And here's a quick tip from my uncle for anyone new to caulking like I am: if you don't finish off the tube, pop a nail or screw in the end. The caulk will seal around it and keep the contents from drying up.