Ask HN: What topics do you think are valuable in secure coding training?

I've been tasked with revamping our onboarding training for secure software development. We have to cater to all skill-sets, from someone just starting out to a senior engineer. Its a one hour session that all new developers at our company have to take, and its currently quite dull. For example, it spends about 15-20 minutes on user password storage/hashing, which is something our developers should never need to do themselves.

What security topics do you think would be valuable for new developers to get exposure to during on boarding?