New reports claim that the mama-of-three banned her ex's new-bae Sofia Richie from attending the event and all other holiday festivities.
And insider told HollywoodLife.com that Kourtney is “ruining his holidays with her jealous, petty ban of Sofia."
The source adds that Kourt has "several issues with Scott dating Sofia and does not like it at all.”
Meanwhile, you'll notice that Kourtney's BF Younes was in attendance at the party.
In fact, the pair were PDA central right in front of Scott which really must've ticked him off considering his girlfriend wasn't allowed to go.
Who knew Kourt could be so petty...?