I can't talk about the 'large part of the customer base' part of this question, but I work in a large (8000+ person) company that runs thousands of servers and I see this mindset of "if it's not tagged as a security issue, we don't really need to apply it" continuously.
Far too many people have the opinion that change, _any_ change should be avoided and so they avoid doing any changes that aren't either tagged as security fixes or causing an outage.
Posted Oct 13, 2011 8:23 UTC (Thu) by Klavs (subscriber, #10563)
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Not to be annoying here - but fact remains, that upgrading to new versions of the kernel, also includes new features, which in turn may add more security problems, than the bugfixes solved.
There's a reason people pay RHEL to backport ONLY fixes (bugs, security etc.) - so the change becomes as little as possible - increasing the likelyhood of the amount of bugs with security impact going down, as time goes by and bugfixes are applied.