Hard to believe but Secure Boot BIOS security has been compromised on hundreds of PC models from big brands because firmware engineers used four-letter passwords
Now, I'll admit my own password hygiene isn't always the best, though I have graduated from the days when I used «xxxxxx» for a few non-critical accounts under the reverse psychology assumption that it's so obviously insecure, nobody would bother trying it. Genius, I know. But even I realise a four-character password is a big no-no.