From : Microsoft

We have today made some new additions to the advisory. We’ve added some new information about the impact of some of the workarounds on systems with 15 character, or longer, system names. We’ve also noted that it is possible for a user with valid logon credentials to access the vulnerability over port 445. As always, we’re continuing to work around the clock to monitor the situation closely, continue our technical investigations and develop a security update to address this issue.