California Code, Corporations Code - CORP § 5214

Subject to the provisions of subdivision (a) of Section 5141 and Section 5142, any note, mortgage, evidence of indebtedness, contract, conveyance or other instrument in writing, and any assignment or endorsement thereof, executed or entered into between any corporation and any other person, when signed by any one of the chairperson of the board, the president or any vice president and by any one of the secretary, any assistant secretary, the chief financial officer or any assistant treasurer of such corporation, is not invalidated as to the corporation by any lack of authority of the signing officers in the absence of actual knowledge on the part of the other person that the signing officers had no authority to execute the same.