Ubuntu announced its 11.04 (Natty Narwhal) release almost 18 months
ago, on April 28, 2011. As with the earlier releases,
Ubuntu committed to ongoing security and critical fixes for a period
of 18 months. The support period is now nearing its end and Ubuntu 11.04
will reach end of life on Sunday, October 28. At that time, Ubuntu
Security Notices will no longer include information or updated packages
for Ubuntu 11.04.

The supported upgrade path from Ubuntu 11.04 is via Ubuntu 11.10.
Instructions and caveats for the upgrade may be found at
https://help.ubuntu.com/community/OneiricUpgrades. Ubuntu 11.10
continues to be actively supported with security updates and
select high-impact bug fixes. All announcements of official security
updates for Ubuntu releases are sent to the ubuntu-security-announce
mailing list, information about which may be found at
https://lists.ubuntu.com/mailman/listinfo/ubuntu-security-announce.

Since its launch in October 2004 Ubuntu has become one of the most
highly regarded Linux distributions with millions of users in homes,
schools, businesses and governments around the world. Ubuntu is Open
Source software, costs nothing to download, and users are free to
customise or alter their software in order to meet their needs.

Kate Stewart
Ubuntu Release Manager