Canonical is providing Extended Security Maintenance for the popular Ubuntu 12.04 LTS release. See the official blog post for more information.
During the official lifetime of an Ubuntu release, Canonical provides security maintenance to binary packages that reside in the main and restricted components of the Ubuntu archive. This FAQ entry contains more information.
During the Extended Security Maintenance phase of the Ubuntu 12.04 LTS release, Canonical will provide security maintenance to binary packages that reside in main originating from the following source packages: