recaptcha still submits form when one word invalid

Question

Um so I was in for a little bit of a surprise tonight. I spent a good 20 mins trying to figure out why I was able to submit a form knowing that what I entered into the recaptcha field was invalid. Is it true that you don't need to input the exact words it displays? If it shows me two words and I misspelled one of the words, I still pass validation? Same goes if "hello world" and I input "hell man" it still works.

Answer 1

With recaptcha, you are only tested on one of the words, while the other is used to help computers in scanning printed material. So you only need to get one right to pass (which one you need is random). :D