Emergency production issue fix

Hi,

I want to know if suppose there is an emergency fix in Production model how will it be performed.

eg. I have one development model and one UAT model after the UAT is done data is pushed from development model to Production model but the push of data is done at the end of the sprint. If in between the sprint cycle there is some  emergency production issue then what should be steps and good practice to fix it.

Thanks 

Pankhuri