uutils coreutils chroot Local Privilege Escalation and chroot Escape in via Name Service Switch (NSS) Injection

A vulnerability exists in the chroot utility of uutils coreutils when using the --userspec option. The utility resolves the user specification via getpwnam() after entering the chroot but before dropping root privileges. On glibc-based systems, this can trigger the Name Service Switch (NSS) to load shared libraries (e.g., libnss_*.so.2) from the new root directory. If the NEWROOT is writable by an attacker, they can inject a malicious NSS module to execute arbitrary code as root, facilitating a full container escape or privilege escalation.