By having access to cellphone numbers and email addresses, spies and hackers could attempt to intercept communication to and from these lawmakers, particularly those on sensitive committees that oversee things like intelligence and the military.

And in making the information public, the hackers sowed fear among a number of Democrats that they were being watched. The lawmakers hadn’t been warned that their information had been stolen before its publication late Friday.

Close to 24 hours after the lawmaker spreadsheet was posted on Guccifer 2.0’s WordPress account, another site, DCLeaks.com, released internal records from George Soros’s Open Society Foundations, a pro-democracy group, including its 2014 priorities in places like Afghanistan, Armenia and Macedonia. Mr. Soros is a large-scale contributor to liberal causes.

DCLeaks.com previously published the content of emails and records connected to the Democratic Party, as well as those of retired Air Force Gen. Philip Breedlove, a former supreme commander of the North Atlantic Treaty Organization. It also released emails from Republican Party operatives, though those messages were fairly limited and mundane.