The remote host is missing an update to samba announced via advisory USN-1075-1.
Details follow:
Volker Lendecke discovered that Samba incorrectly handled certain file descriptors. A remote attacker could send a specially crafted request to the server and cause Samba to crash or hang, resulting in a denial of service.
Solution: The problem can be corrected by upgrading your system to the following package versions:
Ubuntu 6.06 LTS: samba 3.0.22-1ubuntu3.14
Ubuntu 8.04 LTS: samba 3.0.28a-1ubuntu4.14
Ubuntu 9.10: samba 2:3.4.0-3ubuntu5.8
Ubuntu 10.04 LTS: samba 2:3.4.7~ dfsg-1ubuntu3.4
Ubuntu 10.10: samba 2:3.5.4~ dfsg-1ubuntu8.3
In general, a standard system update will make all the necessary changes.