What are the potential security risks of allowing users to modify session variables?

Allowing users to modify session variables can lead to security risks such as session hijacking, data tampering, and privilege escalation. To mitigate these risks, it is important to validate and sanitize user input before assigning it to session variables. 

// Validate and sanitize user input before assigning it to session variables
if(isset($_POST['username'])){
    $username = filter_input(INPUT_POST, 'username', FILTER_SANITIZE_STRING);
    $_SESSION['username'] = $username;
}

Keywords

Session hijacking Cross-site scripting (XSS) Data tampering Session fixation Insufficient validation

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