Kohana is an open source, object oriented MVC web framework built using PHP5 by a team of volunteers that aims to be swift, secure, and small.
Anything can be extended using the unique filesystem design, little or no configuration is necessary, error handling helps locate the source of errors quickly, and debugging and profiling provide insight into the application.
To help secure your applications, tools for input validation, signed cookies, form and HTML generators are all included. The database layer provides protection against SQL injection. Of course, all official code is carefully written and reviewed for security.