stolen from another site but thought it might help
"first check for contamination, pull master cylander cap off, if it has rubber underneath the cap and it's expanded or heavily distorted a petroleum product (such as oil) is in the system. the whole brake system will have to be redone, including brake hoses, mc, prop valve, height sensor, and any thing else rubber relatted in the system. also over adjusted rear brakes or over adjusted e brake can cause this. but check for contamination first this is a serious saftey issue."
I would agree that there is the possibility of contamination, a good system flush would be the best fix for that.
what type of car and ABS on it?
GO LEAFS GO