Heat oil in a heavy pan and add the popcorn. Cover pot and wait for kernels to pop. Shake pot occasionally and wait for kernels to stop popping.
Line two baking sheets with foil and preheat oven to 250°F. Divide popped corn between the two prepared baking sheets.
Melt vegan butter, brown sugar, corn syrup, and salt in a small pan and bring to a boil, stirring constantly. Once boiling, let boil for 5 minutes without stirring. Stir in the Buffalo sauce and boil for another 2 minutes.
Remove from heat and stir in the cayenne pepper and baking soda. Divide the sauce evenly among the two sheets of popcorn. Stir to coat.