The fracture, he said, may be external damage and is believed to be the result of a micro-meteorite.
NASA confirmed the problem and said it consisted of a "minute pressure leak", which crew members were repairing.
In a status update, NASA said the leak was isolated to a hole that's about 2 millimeters (0.07 inches) in diameter in the orbital compartment of Russia's Soyuz MS-09 spacecraft, which is attached to the Russian-built Rassvet module on the station.
The leak was detected on Wednesday night - possibly from a micrometeorite strike - when it caused a small drop in cabin pressure.
Once the hole was identified, crewmembers applied Kapton tape, which slowed the leak.
"As flight controllers monitored their data, the decision was made to allow the Expedition 56 crew to sleep since they were in no danger", NASA said.More news: Matt Smith Joins 'Star Wars: Episode IX' Cast!
The Soyuz docked at the ISS in June bringing three astronauts to the orbiting laboratory 250 miles above the planet. NASA officials said the hole was discovered in part of the Soyuz that does not return to Earth. "Once the patching is complete, additional leak checks will be performed".
Troubleshooting and fix work continued.
Alexander Gerst, a European Space Agency astronaut, reportedly put his finger over the hole initially. Feustel commands the crew.
Astronauts are continuing to try and plug the leak but NASA and Russian officials have stressed the six astronauts are not in any danger.
The space station, which has been continuously occupied since November 2000, has an internal pressurized volume equal that of a Boeing 747, according to NASA.