What occurs when information is spilled from a higher classification level to a lower classification level in the government?

When classified information is given to someone without the security clearance to have that information, it is considered an unauthorized disclosure. Depending on the nature of the classified information that was shared, the penalty for doing so can range from a reprimand to termination. However, if the information is a matter of national security, the individual who leaked the information could face criminal charges, including treason.