The remote host is missing an update to acpid announced via advisory USN-766-1.

The problem can be corrected by upgrading your system to the following package versions: Ubuntu 6.06 LTS: acpid 1.0.4-1ubuntu11.2 Ubuntu 8.04 LTS: acpid 1.0.4-5ubuntu9.3 Ubuntu 8.10: acpid 1.0.6-9ubuntu4.8.10.2 Ubuntu 9.04: acpid 1.0.6-9ubuntu4.9.04.2 In general, a standard system upgrade is sufficient to effect the necessary changes. https://secure1.securityspace.com/smysecure/catid.html?in=USN-766-1

It was discovered that acpid did not properly handle a large number of connections. A local user could exploit this and monopolize CPU resources, leading to a denial of service.