STIGQter: STIG Summary: Red Hat Enterprise Linux 8 Security Technical Implementation Guide Version: 2 Release: 8 Benchmark Date: 01 Jul 2026:

The RHEL 8 SSH daemon must prevent remote hosts from connecting to the proxy display.

DISA Rule

SV-230556r1017318_rule

Vulnerability Number

V-230556

Group Title

SRG-OS-000480-GPOS-00227

Rule Version

RHEL-08-040341

Severity

CAT II

CCI(s)

• CCI-000366 - Implement the security configuration settings.

Weight

10

Fix Recommendation

Configure the SSH daemon to prevent remote hosts from connecting to the proxy display.

Edit the "/etc/ssh/sshd_config" file to uncomment or add the line for the "X11UseLocalhost" keyword and set its value to "yes" (this file may be named differently or be in a different location if using a version of SSH that is provided by a third-party vendor):

X11UseLocalhost yes

Check Contents

Verify the SSH daemon prevents remote hosts from connecting to the proxy display.

Check the SSH X11UseLocalhost setting with the following command:

$ sudo /usr/sbin/sshd -dd 2>&1 | awk '/filename/ {print $4}' | tr -d '\r' | tr '\n' ' ' | xargs sudo grep -iH '^\s*x11uselocalhost'

X11UseLocalhost yes

If the "X11UseLocalhost" keyword is set to "no", is missing, or is commented out, this is a finding.

If conflicting results are returned, this is a finding.

Vulnerability Number

V-230556

Documentable

False

Rule Version

RHEL-08-040341

Severity Override Guidance

Verify the SSH daemon prevents remote hosts from connecting to the proxy display.

Check the SSH X11UseLocalhost setting with the following command:

$ sudo /usr/sbin/sshd -dd 2>&1 | awk '/filename/ {print $4}' | tr -d '\r' | tr '\n' ' ' | xargs sudo grep -iH '^\s*x11uselocalhost'

X11UseLocalhost yes

If the "X11UseLocalhost" keyword is set to "no", is missing, or is commented out, this is a finding.

If conflicting results are returned, this is a finding.

Check Content Reference

M

Target Key

2921