[eluser]Alucemet[/eluser]
Most of the top 10 would involve the way you use CodeIgniter, not CodeIgniter itself, and that's because CodeIgniter is a framework, not an application. One of the biggest problems I can see would be that for many CodeIgniter users, they are using other people's libraries, plugins, etc, and without knowing exactly how they work, or if security was even addressed. If you write all of your own code, and if YOU are safe according to OWASP, I don't see any reason why CodeIgniter would fail you.