1.0 based on PCIe 5.0 was released. It allows host CPU to access shared memory on accelerator devices with a cache coherent protocol. The CXL Specification 1.1 was released in June, 2019.

On November 10, 2020, the CXL Specification 2.0 was released. The new version adds support for CXL switching, to allow connecting multiple CXL 1.x and 2.0 devices to a CXL 2.0 host processor, and/or pooling each device to multiple host processors, in distributed shared memory