When the CEO and CFO sign off on the financial statements, they assume an extraordinary amount of risk. If there is fraud occurring in the financial reporting of their company, they will be severely disciplined. I suggest reading up on Sarbanes-Oxley Section 302[0] and the Enron[1] and WorldCom[2] accounting scandals. Sarbanes-Oxley was issued as a response to the aforementioned scandals and lays out the bulk of the risk that a CEO and other executives take on.
[0] https://www.law.cornell.edu/uscode/text/15/7241