The
kernel is the OS core (Ring 0) with full hardware access. Kernel exploits are the most severe — granting complete system control. Protections: ASLR, SMEP, SMAP, kernel integrity checks.
Kernel vulnerabilities are the most dangerous (highest privilege level). Windows Credential Guard isolates LSASS using kernel virtualization. Linux: grsecurity/KSPP patches harden the kernel. Signed kernel modules prevent malicious modules.