is the batter too loose...too much liquid??Try and make the next batch thicker...
Hmm..that is odd..less batter in the cups then...
excessive sugar can cause cupcakes to spill over, too... That's why if you don't scrape the bowl often enough you end up with an extra-sugary bit at the end that turns into a flat, spreading-over cupcake.
I assume this batter works in regular cupcake liners?
You could be filling too high, or you need to crank up your temperature. My home cupcakes used to bake just fine at 350, I'd open the oven and turn them 1/2 way. Then all of a sudden I was having the same problem as you - they were all running over. Same recipes I've been using for years that bake just fine at work! Was making me crazy!
Another problem I realized I was when I was turning them 1/2 way. If I opened the oven door, it door a few minutes for the elements to kick back on and took even longer for the oven to get back to temperature - the loss in heat was making my cuppies deflate and run over.
After lots of trial and error I realized the temperature of my home oven has started going a little off so I now crank it up to 380 (it works for me) and I don't open that oven until I'm sure they are at least 95% done. Problems solved.
I live at an altitude of almost 4800 feet above sea level. I have overflow issues if I fill my cupcake liners, or even my cake pans, more than 1/2 full. It's taken a bit of trial and error, but I finally got it figured out for my cupcakes, and for my cakes, I use the collar method so that I can fill them just a bit fuller and get a nice 2" high cake without having to worry about the batter overflowing. Altitude, it drives me crazy!! 
Quote by @%username% on %date%
%body%