How should I get the far plane vertex data of the view frustum

I want to get the vertex data of the far plane of the view frustum, but I found that in cesium, I can’t get the correct upward direction of the view frustum I created. I want to know how to get the four far planes of any view frustum. The coordinates of the vertex

https://sandcastle.cesium.com/#c=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