The explanation you linked to has some technical inaccuracies (for one it's not the malloc that causes the problem, it's the actual copy a few lines down). The error is your standard unchecked unsafe memcopy operation. Basically an attacker can read up to 64Kib of the SSL server, whatever happens to be stored there is the attackers (even server password files). You also shouldn't change passwords on a website until the certs are updated, otherwise your new password might be compromised too. You should also change all of your passwords. As pointed out, even if a frontend system isn't vulnerable something on the backend might be. Last time I had my password compromised (KickStarter) I switched to using a password manager, it makes these things much easier to deal with.