are you affected?

• is your sshd running on musl? (alpine, openwrt, buildroot, yocto)
• is it not using pam? alpine's openssh-server doesn't by default, or maybe you set UsePAM no
• are password logins still on? they are by default
• is there an account with just * as its password? key-only users, ldap users, root on alpine
• and some other account with a real password?
• then that * account takes any password between 257 and 1024 characters

on alpine's official aws and azure images that's the default alpine user, and it has passwordless doas. so it's root

on debian, ubuntu, fedora or anything else with glibc? going through pam? dropbear? openbsd? you're fine