Latest secure kernels available in the repos for 32 (pae and non-pae) and 64 bit architecture.
5.6.10 (antiX-17, antiX-19, testing and sid)
4.19.120 (antiX-17, antiX-19, testing and sid)
4.9.221 (antiX-17, antiX-19, testing and sid)
4.4.221 (antiX-16, antiX-17, antiX-19)
Note: The 5.6.10 kernel might not build broadcom-sta wifi, nvidia drivers or virtualbox drivers (yet).