On ct the doctors found multiple exophytic solid masses on bilateral kidneys. what is the likely diagnosis, cancer?

Could be: Different things- including benign tumors ( like lipoma, stromal tumor, adenoma, fibroma etc)- , however malignancy is something that is absolutely has to be ruled out. You need a biopsy of the kidney mass definitively. Discuss further with your doctor.

See a Urologist.: Solid masses found on kidneys are more concerning than fluid-filled lesions. You should see a urologist for further evaluation of these lesions. Best of luck to you.