Only if you don't use an SSH agent. If you use an agent to store your keys, they are safe. Even if your keys leak because you're not using an agent, they can only leak in encrypted form (you use passphrases, don't you?). When the vulnerability is about to be triggered, a strange message (connection suspended, press return to resume) appears and must be dismissed (if you ^C at that point, you are safe).
In otherwords, this is a panic situation only for people using non-passphrased keys and no SSH agent. You also have to accept a prompt that is not normal and should raise red flags before the vulnerability can happen. People who fit that description probably have other security problems to worry about.
More realistically, you should patch your servers if you use any kind of SSH-based automation (e.g. where one master server uses SSH to automate tasks on slaves), since this allows an attacker to escalate from a target machine to the automation machine. But that requires first compromising the target, so it is not an emergency situation (unless your machines are already compromised and you don't know it, in which case, again, you have bigger problems).