We asked our admin to update SVN on our CentOS 6.5 server. He did so and the result was SVN 1.6.11. However the current version of SVN is 1.8.9.
I know the CentOS yum repository is not always up-to-date. But in that case I am confused: SVN 1.6.x is not officially supported anymore. This means it does not get any security fixes!
How can the official CentOS repository provide such an old (and dangerous) version? Is there something we (or our admin) understood the wrong way?
As an enterprise distribution, Red Hat locks packages in the distribution to a specific version, so that the features offered are known and consistent and do not change behavior unexpectedly during the lifetime of the installation.
As you noted, this means the version of software can be "old."
However, they also backport security fixes when available, applying them to the old version. For instance, a number of security fixes have been made for subversion over the life of the distribution. This allows for keeping a secure system without the risk of breakage caused by the introduction of new functionality (which does happen from time to time).
You can obtain information about specific security fixes at Red Hat's site by searching for the CVE number.
Or, to see the change history of the package online, try:
rpm -q --changelog subversion
You'll see the most recent entries first, starting with:
* Wed Feb 12 2014 Joe Orton <jorton@redhat.com> - 1.6.11-10
- add security fixes for CVE-2013-1968, CVE-2013-2112, CVE-2014-0032
CentOS (or really, RHEL with CentOS along for the ride) commits to supporting the version they're distributing until the OS is end of life; they are responsible for backporting security fixes to the old/unsupported version.
The reason for this is stability; they don't upgrade major versions of software within a major OS version in order to not break application compatibility on regular updates. EL 6 is definitely getting to the point where some of those packages are pretty old simply due to its age and when those package versions were locked in; EL 7 is just around the corner.
SVN 1.6 may not be supported upstream any longer; but you didn't buy it from upstream, so it's not really relevant. The moment you installed an enterprise distro, your route to software is largely through the distro. Years of people grabbing this week's release has jaded people into thinking that's scalable, safe, consistent or reliable. You may be able to find an alt-package for some software, but like a 6 year old BMW with only Bluetooth 4.0 and no major engine replacements since, you should know it's not a bad sign.
