John works as a professional Ethical Hacker. He is assigned a project to test the security of www.weare- secure.com. He enters a single quote in the input field of the login page of the We-are-secure Web site and receives the following error message:

Microsoft OLE DB Provider for ODBC Drivers error '0x80040E14'

This error message shows that the We-are-secure Website is vulnerable to __________.