If you're referring to Cubit, they license the ACIS kernel under the hood.

They’re (possibly) referring to “Scalable Geometric Modeler” (SGM)

https://github.com/sandialabs/sgm

Originally open-source, but since taken back in-house. As I understand, which should not be construed as an accurate accounting, Sandia wants to flesh out the basics further before (potentially) open-sourcing it again.