[CentOS] when RedHat makes patches for only some versions

I guess this is really a RedHat, not CentOS question, but I’m hoping that someone here will be familiar enough with the upstream policy to have some useful information.

How does RedHat decide which versions to release patches for, e.g. https://access.redhat.com/security/cve/CVE-2015-7613 <https://access.redhat.com/security/cve/CVE-2015-7613> which has only a RH7 erratum, not 6?  And are they likely to eventually release a fix for this type of issue for RH6?

								thanks,
								Noam
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Noam Bernstein
Center for Materials Physics and Technology
Naval Research Laboratory Code 6390

noam.bernstein at nrl.navy.mil
phone: 202 404 8628