Preheat the oven to 350 degrees F (175 degrees C). Grease the bottom and sides of a fluted tube pan (such as Bundt® generously.

Beat sugar and butter together in a bowl with an electric mixer until light; beat in eggs, one at a time, mixing well after each addition. Reduce mixing speed and add poppy seeds, lemon zest, and vanilla extract.

Combine flour, salt, baking soda, and baking powder in another bowl. Beat in flour mixture slowly, alternating with buttermilk.

Spoon batter into the prepared pan.

Bake in the preheated oven until a toothpick inserted into the center of the cake comes out clean, 65 to 75 minutes.