Cubemap edge clamping doesn't seem to work?

My sampler is created with address mode U, V, and W all set to addressModeU. The flags parameter of the samplercreateinfo structure includes the VK_SAMPLER_CREATE_NON_SEAMLESS_CUBE_MAP_BIT_EXT value. Yet cubemap faces are still “leaking” along the edges when linear filtering is enabled:

Using nearest filtering shows that the cubemap pixels are not the problem:

Windows 10, GEForce 1660

It’s hard to tell what the problem is or what the desired outcome is without knowing how you’re using this cubemap.

I’m pretty sure this is a driver bug. In the first image, the bottom face of the cubemap is “leaking” into the linear texture sample.