What are some potential issues that may arise when passing variables in URLs in PHP?

One potential issue that may arise when passing variables in URLs in PHP is the risk of injection attacks if the input is not properly sanitized. To solve this issue, it is important to validate and sanitize the input before using it in your application.

// Sanitize input before using it in your application
$variable = isset($_GET['variable']) ? filter_var($_GET['variable'], FILTER_SANITIZE_STRING) : '';