make-initrd-ng is a tool for copying binaries and their dependencies. Local privilege escalation affecting all NixOS users. With systemd.shutdownRamfs.enable enabled (the default) a local user is able to create a program that will be executed by root during shutdown. Patches exist for NixOS 24.11 and 25.05 / unstable. As a workaround, set systemd.shutdownRamfs.enable = false;.
Opening temporary files without appropriate measures or controls can leave the file, its contents and any function that it impacts vulnerable to attack.