I made some statistics and comparisons about security advisories published by three popular RHEL 6 clones: CentOS 6, Oracle Linux 6 and Scientific Linux 6.
The article is available at the following URL:
I hope you find it interesting. Looks like CentOS has been doing quite well this year in this regard.
Feedback is welcome, but please post it at the bottom of the article or to myself in private. Do *not* send it to this mailing list unless your message is specifically about CentOS. Please do not start a flame war on this mailing list.
In case the graphs are not visible in your browser, you should start using a browser which supports current technologies (specifically: SVG