Well, according to People magazine, the answer is yes and the secret romance has been going on for a good few months.
A source told the mag that it's not serious, it's just a bit of fun for Kourt and JB.
"It's just one of those things where it makes Kourtney feel good about herself. It's not serious at all. This young guy is into her, he thinks she's hot and she's older. She just wants to have fun," said the insider.
Another source told Us Weekly: "Justin and Kourtney have been hooking up since late August, early September."
Kourtney, 36, and Justin, 21, sparked romance rumours last week when they were apparently spotted being "super touchy feely" at a celebrity hotspot in Los Angeles.
They were also seen leaving a club together in October.
Kourtney split from partner of nine years Scott Disick in July. He's the father of her three children, Mason, six, Penelope, three, and Reign, one. Justin's last serious relationship was with Selena Gomez.
All you need to know about Kourtney Kardashian:
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