https://phys.org/news/2018-08-small-air-leak-russian-capsule.html

The leak was detected Wednesday night—possibly from a micrometeorite strike—when it caused a small drop in cabin pressure. It was traced to a hole about 2 millimeters (less than one-tenth of an inch) across in a Soyuz capsule docked at the space station.

Thursday morning, the crew taped over the hole, slowing the leak. Later, the two Russian spacemen put sealant on a cloth and stuck it over the area, while their colleagues took photos for engineers on the ground. Flight controllers, meanwhile, monitored the cabin pressure while working to come up with a better long-term solution.