A contemporary and very controversial example of a media leak is the Edward Snowden leaks of NSA classified material.
Explanation:
Edward Snowden, a subcontractor who worked for the National Security Agency had been collecting classified information throughout his association with the agency. In 2013, after he flew to Hong Kong with the classified material, he handed over the documents to a journalist who worked for 'The Guardian'.
The federal government charged Snowden with the violation of the Espionage Act of 1917 and for stealing classified government documents and sharing them with people who were not authorized to possess the documents. The documents were particularly related to the surveillance activities carried out by the NSA over American citizens.