Cubas intercepted a clearing attempt, taking the ball off his chest at the top of the penalty area, and fired a right-footer past former Whitecaps goalkeeper Maxime Crepeau and into the bottom-left corner.
Vancouver improved to 7-8-3. MLS-leading LAFC dropped to 11-4-3.
Crepeau made a save in his return to BC Place. Jeers and boos rained down on the 28-year-old Canadian nearly every time he touched the ball.
Crepeau started 32 games for Vancouver between 2019 and 2021 but requested a trade ahead of the 2022 season because of what Whitecaps sporting director Axel Schuster has described as a “very personal situation.”
Vancouver goalkeeper Cody Cropper did not have a save but recorded his fourth shutout of the season.
This story originally appeared in Los Angeles Times.