The cable network cites unidentified "U.S. officials" and points to an article published Tuesday in The Intercept, the news site of Glenn Greenwald, who has done much of the reporting on Snowden documents.
The article cites secret documents from August 2013, after Snowden, a former contractor for the National Security Agency, had flown to Russia.
The article reports that more than 40 percent of the people in the government's terrorist database are not connected to any terrorist group.
A spokesman for the Office of the Director of National Intelligence declined to comment on the CNN report on Tuesday.
The possibility of a second person revealing information has been discussed for some time. Greenwald wrote on Twitter on July 4 that it "seems clear at this point" that there is a second person leaking documents.
Two articles in the German press have reported on national security issues without citing Snowden, raising the possibility that they received the information from a different source.
“That's particularly notable given that virtually every other article using Snowden documents — including der Spiegel — specifically identified him as the source,” Greenwald said in an email to The Hill last month.
Greenwald declined to say whether he had additional sources during a CNN interview in February, but did say, "I have no doubt that there will be other sources inside the government who see extreme wrongdoing who are inspired by Edward Snowden."
— Julian Hattem contributed.