A Soyuz capsule that was docked at the space station was probably hit by a micrometeorite, and it had a 2 millimeters hole which caused a small pressure drop in the cabin.
Flight controllers at NASA Mission Control Center in Houston worked with their Russian counterparts to enable the repairs.
"Soyuz commander Sergey Prokopyev of Roscosmos used epoxy on a gauze wipe to plug the hole identified as the leak source", says NASA on a blog post.
"Our obligations under the NASA contract to deliver American astronauts to and from the ISS end with the Soyuz-MS landing in April", Russia's Deputy Prime Minister Yury Borisov was quoted as saying by Interfax.
A leak on the space station could come from a seal or valve failing, said John Crassidis, an aerospace engineer at the University at Buffalo.
"Right now, Alex has got his finger on that hole and I don't think that's the best remedy for it", someone from NASA's ground control team said during a live feed of the fix operations broadcast from the ISS.
The next morning, the team probably woke up to some surprising (and slightly worrying) news, and all crew members went searching for the hole. The makeshift repairs seem to have stabilized the situation, at least for now, officials said.
The leaking Soyuz - one of two at the station - arrived at the orbiting lab in June with three astronauts. The capsule will also have to bring them back home in December. NASA signed an accord in 2017 to acquire extra Soyuz seats into 2019, even though no further contracts involving the Russian craft have been announced. Nasa said it was premature to suggest the astronauts may have to return home if the leak continues to be a problem.
For the six astronauts on the 250-mile-high ISS, now home to three Americans, two Russians and one German, things like orbital debris is always constant threat, even the tiny 2mm pieces.
Both natural micrometeoroids (bits of rock left over from the formation of our solar system) and space debris (small pieces of spacecraft that still orbit Earth) are travelling at incredible speeds through space.