A source close to the situation has confirmed that the fight did in fact happen, and it's not just a rumor. This was first reported by Justin Labar.
Hearing backstage #WWE fight took place overseas involving repeat offender. Have doubts on if he has leverage to work in his favor.— Justin LaBar (@JustinLaBar) November 6, 2016
Jericho reportedly seemed to get the better of this brawl. Both Jericho and Sin Cara are known to be tough guys outside of their wrestling characters, and that it’s not the first time that both men have been involved in backstage altercations. Sin Cara was involved in a backstage fight with Simon Gotch prior to a Smackdown taping a few months ago and Jericho got into an altercation with Brock Lesnar after SummerSlam.
It’s not yet clear if WWE will discipline both men or who started the fight or why it happened in the first place.