Steps to reproduce :
- Start a fresh wiki
- Create a new user, let's call it "Bob"
- Update the section "Users & Rights > Registration" of the administration, so that passwords require at least 12 characters
- Bob lost his password, use the "Reset password" functionality to get an email with a reset password link
- Clicking on the link, you can update Bob's password, but here you can put a weak password, something like "Yolololo", which is not 12 chars long.