There have been various bugs and security flaws found in different versions of Android. Many have been pached in newer versions, but the non-updated devices remain bugged/vulnerable.
My questions are:
Are all Androids with the same version bugged/vulnerable in the same way, e.g., does a Samsung running 4.0 have the same problems as a Sony running 4.0 or as a Nexus device running 4.0?
Is there an overview somewhere what bugs (and especially which security flaws) are there in which versions? Many devices sold today do not run the newest Android; can I tell before buying which bugs/security problems I might encounter? (I am not interested in missing features introduced by newer versions)
Just to make it clear: bugs that can be solved by updating some apps are not relevant. (They are relevant if the update solving the issue would require a newer Android version).