Gareth Heyes has a new post today talking about one of the vulnerable values in the $_SERVER superglobal - PHP_SELF.

I thought it might be a good idea to gather a few test cases demonstrating the problem. Why PHP allows these URL's is beyond me and it wouldn't take much work to filter out these malicious URL's in the PHP code.

He provides four test cases to show how simple it is to abuse - one using a HTTP header, another pushing XSS through, the third mentions search pages and the fourth a direct code injection.

You can download the code here.