A vulnerability has been discovered in SSL3.0 and it's called Poodle. That SSL3.0 has issues is not new, but after this discovery there is no excuse left to keep using it.
Although Hiawatha has support for SSL3.0, it is disabled by default. So, unless you have changed this behaviour via the MinSSLversion, you have nothing to worry about. In the next release, I will completely remove the support for SSL3.0. No more more leniency for WindowsXP and IE8 users.