The macOS system must disable the guest account.

STIG ID: APPL-14-002063  |  SRG: SRG-OS-000364-GPOS-00151 |  Severity: medium |  CCI: CCI-001813 |  Vulnerability Id: V-259511 | 

Vulnerability Discussion

Guest access must be disabled.

Turning off guest access prevents anonymous users from accessing files.

Check

Verify the macOS system is configured to disable the guest account with the following
command:

/usr/bin/osascript -l JavaScript << EOS
function run() {
let pref1 = ObjC.unwrap($.NSUserDefaults.alloc.initWithSuiteName('com.apple.MCX')\
.objectForKey('DisableGuestAccount'))
let pref2 = ObjC.unwrap($.NSUserDefaults.alloc.initWithSuiteName('com.apple.MCX')\
.objectForKey('EnableGuestAccount'))
if ( pref1 == true && pref2 == false ) {
return("true")
} else {
return("false")
}
}
EOS

If the result is not "true", this is a finding.

Fix

Configure the macOS system to disable the guest account by installing
the "com.apple.MCX" configuration profile.