Squeaking noise in brake pedal

I have a 2006 Acura MDX with 90K miles. It has developed a very loud and annoying squeaking noise when you press the brake pedal. It’s not the pads or rotors…it’s from the actual pedal itself on the inside of the car. Other than being very annoying it does not do anything unusual or present a problem. However, it’s annoying me. Can anyone offer any suggestions on how to fix? I’ve tried WD40…no improvement. Thanks in advance.

It might be the push rods inside the brake master cylinder. Since the cylinder is mounted against the firewall, the sound might appear to be coming from the pedal.

The power brake booster may be leaking, it operates with engine vacuum. Do you hear this noise when applying the brake with the vehicle in park? Does the pitch change when moving the pedal?

Do you hear the noise with the engine off (and off for a few minutes) ? That would rule out (I think) the power brake booster.

For it to be as loud as you report OP, seems like it almost has to be the power brake booster. There are other things that can squeak as a result of braking, but unless it was coming from the wheels, the squeak wouldn’t normally be very loud.