How to fix X forwarding broken by Aug 09 EIS on Solaris

Quite a while back, encountered X forwarding broken for many of the servers.

Basically, this is caused by the SSH patch due to regression in SSHD

Solaris 9 with patch 122300-28 or later
Solaris 10 with patch 126133-03 or later
Solaris 10 with patch 138060-03 and without patch 138060-04

To work around this issue, the following command can be executed as root user:
# ifconfig lo0 inet6 plumb up

More information can be found in this article - sun link