Canonical released last night, November 29th, a new kernel update for its Ubuntu 11.04 (Natty Narwhal) operating system, fixing several more security vulnerabilities discovered in the Linux kernel packages by various hackers.
As usual, you can click on each one to see how it affects your Ubuntu 11.04 operating system, or go here for an in-depth description. The security flaws can be fixed if you upgrade your system(s) to the linux-image-2.6.38-13 (2.6.38-13.52) package(s).
To apply the updates, run the Update Manager app. Don't forget to reboot your computer after the upgrade!
ATTENTION: Due to an unavoidable ABI change, the kernel packages have a new version number, which will force you to reinstall and recompile all third-party kernel modules you might have installed. Moreover, if you use the linux-restricted-modules package, you have to update it as well to get modules which work with the new Linux kernel version.