Attackers can cause a crash in SSH servers when the server has been configured by passing a Signer to ServerConfig.AddHostKey such that 1) the Signer passed to AddHostKey does not implement AlgorithmSigner, and 2) the Signer passed to AddHostKey returns a key of type “ssh-rsa” from its PublicKey method.
Servers that only use Signer implementations provided by the ssh package are unaffected.