Aug 2018 SAT--apparently a repeat of the Oct 2017 International SAT, so some people had seen the test already.

College Board has not said that it will invalidate all scores; currently, College Board is saying that it will invalidate only the scores of those they determine cheated.

I've heard a bunch of anecdotal comments about people who knew people who had seen the test before, even one person who announced at the end of the test that it was 'easy' and he'd 'taken that test before'. (The proctor asked him to stay behind!)

A lot of my students are asking me if College Board will invalidate all scores. I find that difficult to imagine--too many plans (and lives, even) could be affected, disrupted, or even ruined. For example, a student has friends whose only chance to take the SAT (with little pressure) occurred in August--they are very high-achieving students planning to apply to top-ten universities, and their application plans are not allowing for a retake of the SAT Reasoning Test.