The latest version of Ubuntu still in beta is 11.10 (Oneiric). It ships Apache 2.2.20 which includes important vulnerabilities fixes.
When you are in a situation like this you need to look for available debian repositories. A good place to search for them is http://repogen.simplylinux.ch/
From the site you will be able to obtain the sources.list file for any Ubuntu distro. Once you have the entries you need to add them locally and then run some commands.
So here is what you can do to upgrade Apache to 2.2.20 in Maverick (and probably other Ubuntu versions)
$ sudo vi /etc/apt/sources.list ... deb http://us.archive.ubuntu.com/ubuntu/ oneiric main ... $ sudo apt-get update $ sudo apt-get install apache2 $ apache2 -v Server version: Apache/2.2.20 (Ubuntu) Server built: Sep 6 2011 18:40:05 $ sudo vi /etc/apt/sources.list ... #comment it out or delete it completely #deb http://us.archive.ubuntu.com/ubuntu/ oneiric main ... $ sudo apt-get update