[CentOS] A potentially newbie question about vulnerability patching speed in CentOS 7.x's yum repository

I've been dubbing with management of security vulnerabilities and their fixes for a while, recently I discovered there may be a delay in the process of software updates made available on CentOS yum repository. 


take CVE-2017-5335 for example:
In redhat official notice board :https://access.redhat.com/security/cve/cve-2017-5335  we can see there is a link point to advisory for RHEL 7: https://access.redhat.com/errata/RHSA-2017:2292 . from there we can see that the fix happens at gnutls 3.3.26. 
But when trying to update with yum update from a CentOS 7.3 x64 machine. there is no 3.3.26 available. Only available rpm for CentOS 7.3.1611 for x86_64 is gnutls-3.3.24.
This result can be verified using rpm finder: https://www.rpmfind.net/linux/rpm2html/search.php?query=gnutls




Same problem happens to other software packages such as:
glibc
tcpdump
libnl
mariadb
...
(and many others)


Why is that? and are those software packages not going to get fixed?


- p.s. please excuse me for any formating issues.  :) 


Jeff