Current Fedora versions that were installed as Fedora 39 are affected.
It you used an rpm-ostree version of Fedora since it was on 38 or below, and upgraded to 39, you are not affected.
The update with the fix rolls out today. As a workaround you can use this
sudo chmod --verbose 0000 /etc/shadow /etc/gshadow /etc/shadow- /etc/gshadow-
It is recommended to change all credentials stored there, i.e. at least your user(s) password(s).
If you use dnf you are not affected, yes