Canonical issued last night, February 13th, new versions of the Linux kernel packages for the Ubuntu 11.04 (Natty Narwhal) and Ubuntu 10.10 (Maverick Meerkat) operating systems, fixing vulnerabilities found recently in the official Linux kernel packages.The following four Linux kernel vulnerabilities were found: CVE-2011-3353, CVE-2011-4622, CVE-2012-0038, and CVE-2012-0044.
As usual, you can click on each one to see how it affects your system, or go here and here for in-depth descriptions, as it affects other Linux operating systems as well.
The security flaws can be fixed if you update your system(s) to the linux-image-2.6.35-32 (2.6.35-32.65) package(s) for Ubuntu 10.10 and the linux-image-2.6.38-13 (2.6.38-13.55) package(s) for Ubuntu 11.04.
For in-depth instruction about how to update your system, please follow this link: https://wiki.ubuntu.com/Security/Upgrades. Don't forget to reboot your computer after the upgrade!