What are some common pitfalls to avoid when implementing file access control in PHP?

One common pitfall to avoid when implementing file access control in PHP is not properly sanitizing user input before using it to access files. This can lead to security vulnerabilities such as directory traversal attacks. To prevent this, always validate and sanitize user input before using it in file operations. 

// Incorrect way: not sanitizing user input
$file = $_GET['file'];
$data = file_get_contents("/path/to/files/" . $file);

// Correct way: sanitizing user input
$file = basename($_GET['file']);
$data = file_get_contents("/path/to/files/" . $file);

Keywords

file access control PHP security permissions vulnerability

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