What potential issues can arise when using $_SESSION variables in PHP?

One potential issue when using $_SESSION variables in PHP is the possibility of session hijacking, where an attacker can steal a user's session data and impersonate them. To prevent this, it's important to use secure session handling techniques such as regenerating the session ID after a user logs in or out, using HTTPS to encrypt the session data, and setting appropriate session configuration options. 

// Start a secure session
session_start([
    'cookie_lifetime' => 86400, // set the session cookie to expire in 1 day
    'cookie_secure' => true, // only send the cookie over HTTPS
    'cookie_httponly' => true, // prevent client-side scripts from accessing the cookie
]);

// Regenerate the session ID to prevent session fixation
session_regenerate_id(true);

Keywords

$_SESSION security vulnerabilities session hijacking data manipulation session fixation

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