RHEL 9 must enable mitigations against processor-based vulnerabilities.

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
low	V-257795	SRG-OS-000433-GPOS-00193	RHEL-09-212050	SV-257795r1044845_rule	2025-02-27	2

Description
Kernel page-table isolation is a kernel feature that mitigates the Meltdown security vulnerability and hardens the kernel against attempts to bypass kernel address space layout randomization (KASLR). Satisfies: SRG-OS-000433-GPOS-00193, SRG-OS-000095-GPOS-00049

ℹ️ Check
Verify RHEL 9 enables kernel page-table isolation with the following command: $ sudo grubby --info=ALL \| grep args \| grep -v 'pti=on' If any output is returned, this is a finding. Check that kernel page-table isolation is enabled by default to persist in kernel updates: $ grep pti /etc/default/grub GRUB_CMDLINE_LINUX="pti=on" If "pti" is not set to "on", is missing or commented out, this is a finding.

ℹ️ Check

Verify RHEL 9 enables kernel page-table isolation with the following command: $ sudo grubby --info=ALL | grep args | grep -v 'pti=on' If any output is returned, this is a finding. Check that kernel page-table isolation is enabled by default to persist in kernel updates: $ grep pti /etc/default/grub GRUB_CMDLINE_LINUX="pti=on" If "pti" is not set to "on", is missing or commented out, this is a finding.

✔️ Fix
Configure RHEL 9 to enable kernel page-table isolation with the following command: $ sudo grubby --update-kernel=ALL --args="pti=on" Add or modify the following line in "/etc/default/grub" to ensure the configuration survives kernel updates: GRUB_CMDLINE_LINUX="pti=on"