Mysql 6.3 BUG Malformed packet

16:41:01 [ERR][      SqlEditor]: SqlEditorForm: exception in do_connect method: Exception: Malformed packet
16:41:01 [ERR][  GRTDispatcher]: exception in grt execute_task, continuing: Exception: Malformed packet
16:41:01 [ERR][  GRTDispatcher]: worker: task 'execute sql queries' has failed with error:.Malformed packet
16:41:01 [ERR][    WQE backend]: Got an exception during connection: Malformed packet
16:41:01 [ERR][      SqlEditor]: SQL editor could not be connected: Malformed packet
16:41:01 [ERR][      SqlEditor]: Your connection attempt failed for user 'root' from your host to server at XXX:3306:
  Malformed packet

Please:
1 Check that mysql is running on server XXX
2 Check that mysql is running on port 3306 (note: 3306 is the default, but this can be changed)
3 Check the root has rights to connect to XXX from your address (mysql rights define what clients can connect to the server and from which machines)
4 Make sure you are both providing a password if needed and using the correct password for XXX connecting from the host address you're connecting from

Este Bug esta reportado :
http://bugs.mysql.com/bug.php?id=78947

It was a software bug in MySQL Workbench. Upgrading mysql-workbench-community.x86_64 to version 6.3.3-1.fc20 solved the issue.