An unpatched security hole in Ubuntu Linux 8.04 LTS operating system could be used by attackers to send a crafted packet and cause a denial of service via application crash in applications linked against OpenSSL to take control of vulnerable servers. Also ruby package can be used to run a malicious script – an attacker could cause a denial of service or execute arbitrary code with the privileges of the user invoking the program. It is recommended that you immediately update your system. Affected systems:
OpenSSL Vulnerability – Ubuntu Linux LTS 8.04 and corresponding versions of Kubuntu, Edubuntu, and Xubuntu.
Ruby Vulnerability – Ubuntu 6.06 LTS Ubuntu 7.04 Ubuntu 7.10 Ubuntu 8.04 LTS and corresponding versions of Kubuntu, Edubuntu, and Xubuntu.

How do I fix this issue

Simply type the following two commands:
$ sudo apt-get update
$ sudo apt-get upgrade
After a standard system upgrade you need to reboot your computer to effect the necessary change:
$ sudo reboot