Many vulnerbilities involving files and file operations rely on a program accessing a file in a predetermined directory.
If an attacker manipulates the file system in a way that makes that program access a different file than the one intended.
For instance, this is the technique used by many attacks targeting UNIX symlinks and Windows shortcuts.
Once the correct file has been opened, a program is no longer vulnerableto these types of attacks so long as the file is accessed via a file descriptor.
h2 Non-compliant Example 1
h2 Compliant Solution 1