This kernel vulnerability in #FreeBSD is fully mitigated in #HardenedBSD by default: https://www.freebsd.org/security/advisories/FreeBSD-SA-26:21.ptrace.asc

HardenedBSD does not permit ptrace(PT_REMOTE_SC) by default. In fact, multiple sysctl nodes must be toggled to even support ptrace. We have a separate sysctl node for performing syscalls over the ptrace boundary (hardening.prohibit_ptrace_syscall, default 1).