source: https://www.securityfocus.com/bid/26410/info

AutoIndex PHP Script is prone to a remote denial-of-service vulnerability because the application fails to properly handle unexpected input.

Successfully exploiting this issue allows remote attackers to consume excessive CPU resources, potentially denying service to legitimate users.

AutoIndex PHP Script 2.2.2 and 2.2.3 are vulnerable to this issue; prior versions may also be affected.

http://www.example.com/AutoIndex/index.php?dir=%00