Local root code execution via inherited PYTHONPATH

Local privilege escalation in needrestart before 3.8 allows local users to execute arbitrary code as root through a crafted Python process environment. The Python interpreter scanner copies PYTHONPATH from an unprivileged process's /proc environment and then launches Python as root, causing modules from an attacker-controlled path to load. Exploitation requires a local account, interpreter scanning to be enabled, and a privileged needrestart run such as an APT or unattended-upgrades hook.