Root code execution via unvalidated Kerberos cache path

Local privilege escalation in NoMachine Server v8 and v9 allows local users to execute arbitrary code as root via a crafted Kerberos cache path. Command-line handling accepts a user-controlled path to a valid Kerberos cache file and uses it in privileged copy or overwrite operations without proper validation. Low-privileged code execution on the host is required, and successful exploitation permits arbitrary file overwrites or copies as root.