Similarly to ITK, I suggest we use the version available with the Ubuntu Long-Term-Support distribution at the time of the release (this will be 18.04 - Bionic Beaver). This version is currently CMake 3.9.5.
For reference, here is last topic about updating to CMake 3.5.0. See Minimum required version of CMake updated to 3.5.0
Cc: @lassoan @pieper @thewtex
Version of CMake use to build Slicer on Windows and Linux has been updated to 3.10.2
Next, build system will be updated to require CMake 3.9.5