Are there any security concerns to keep in mind when using session variables in PHP?

One security concern when using session variables in PHP is the possibility of session hijacking, where an attacker steals a user's session ID and impersonates them. To prevent this, it's important to regenerate the session ID after a user logs in or changes privilege levels. This can help mitigate the risk of session fixation attacks.

// Regenerate session ID after login or privilege level change
session_regenerate_id(true);