DVWA
PHP/MySQL web application
...Please note, there are both documented and undocumented vulnerabilities with this software. This is intentional. You are encouraged to try and discover as many issues as possible. Damn Vulnerable Web Application is damn vulnerable! Do not upload it to your hosting provider's public html folder or any Internet facing servers, as they will be compromised. It is recommended using a virtual machine (such as VirtualBox or VMware), which is set to NAT networking mode.