Linux distributions don’t update to the latest version of every package. They ship a specific version of an application (such as Apache), and they continue to use that version for the life of that distribution.
Distribution vendors backport bug and security fixes into the version of the application that they’re shipping.
So, whatever version of Apache you’re seeing as available – that’s the most recent version available on CentOS, and contains all the bug and security fixes as provided by CentOS