Description

Ensure that none of the directories in root’s path is equal to a single . character, or that it contains any instances that lead to relative path traversal, such as .. or beginning a path without the slash (/) character. Also ensure that there are no “empty” elements in the path, such as in these examples:

PATH=:/bin
PATH=/bin:
PATH=/bin::/sbin

These empty elements have the same effect as a single . character.

Rationale

Including these entries increases the risk that root could execute code from an untrusted location.