The kernel we use in Gaia comes with different versions of Red Hat Enterprise Linux.
- The 2.6.18 kernel comes with RHEL 5 and is still receiving extended support from Red Hat.
- The 3.10 kernel comes with RHEL 7 and is in production support from Red Hat.
This is obviously a different level of support from the what the Linux kernel team delivers.
Bottom line: the kernels, while older, are fully supported.
It's a lot easier to keep up with potential security vulnerabilities on a stripped-down, hardened OS.
Most of the modifications we make to the kernel and userspace packages are with this in mind.