I think I've seen this question pass by earlier, but don't immediately find it back..
So, I have postgres 9.6.9 and customer wants it to be updated to 9.6.11, because that is their current testing "sandbox" version, which was not installed by me and is also another linux distro.
Now, the newest security update is 9.6.15.. If I download that RHEL repository, I will automatically get that version, and won't be able to choose the exact patch..
So my question is, is there a way to get the 9.6.11 update?
PostgreSQL does not release individual security patches. The way to get the security patch is to install the latest minor version, see https://www.postgresql.org/support/security/.
If you want to get an individual security patch you will have to cherry pick it from git and build your own server from source. But per the above link, it is really recommended that you don't do that. Instead, do it the way it's intended to, which means install the latest minor release.
Why would you not want the other security patches, or other important bugfixes?