The remote host may give an attacker information useful for future attacks.
The remote host is running a version of the SSH daemon older than 3.1.2 or equal to 3.0.0. There is a vulnerability in this release that may, under some circumstances, allow users to authenticate using a password whereas it is not explicitly listed as a valid authentication mechanism. An attacker may use this flaw to brute force a password using a dictionary attack (if the password used is weak).
Upgrade to SSH 3.1.2 or higher.