Steering fluid in brake reservoir

Good morning.

That is not good news. Every component with rubber has to be replaced.

Master cylinder.
Brake hoses.
Calipers.
Wheel cylinders if you have them or rear calipers.
ABS control unit if you have ABS.
Proportioning valve if you do not have ABS.

The issue is that petroleum will swell all the seals and continue until failure. That is why all those parts must be replaced.

Roy