The incident occurred during a preseason game against the Vegas Golden Knights on Sunday.
It's an automatic three-game suspension that the Sharks can appeal, at which point NHL commissioner Gary Bettman could consider a reduction, TSN's Darren Dreger noted.
Kane was ejected from Sunday's heated exhibition contest after an altercation involving Golden Knights defenseman Deryk Engelland and linesman Kiel Murchison. The Sharks winger slashed Murchison in an apparent attempt to whack Engelland, and then shoved Murchison after the official took him down to the ice.
Kane said postgame that the linesman's actions were "an absolute joke."
The Sharks and Golden Knights open the regular season with a home-and-home series beginning Wednesday in Vegas and concluding Friday in San Jose.