AVideo Vulnerable to Reflected XSS via Unsanitized plugin Parameter in YPTWallet Stripe Payment Page

WWBN AVideo is an open source video platform. In versions up to and including 26.0, the YPTWallet Stripe payment confirmation page directly echoes the `$_REQUEST['plugin']` parameter into a JavaScript block without any encoding or sanitization. The `plugin` parameter is not included in any of the framework's input filter lists defined in `security.php`, so it passes through completely raw. An attacker can inject arbitrary JavaScript by crafting a malicious URL and sending it to a victim user. The same script block also outputs the current user's username and password hash via `User::getUserName()` and `User::getUserPass()`, meaning a successful XSS exploitation can immediately exfiltrate these credentials. Commit fa0bc102493a15d79fe03f86c07ab7ca1b5b63e2 fixes the issue.