Now upgrade / installation seems to be completely broken. I did try to install the upgrade, and it failed due to ufilled dependencies (I think someting about dropbear).

As the same thing happened on the last openssh update and back then I was able to solve the problem by completely uninstalling an reinstalling openssh I did try the same thing again.

But now after uninstalling openssh it's not even possible to reinstall it.

Edit: to be more precise, its' not possible to install openssh-client and therefore also not the openssh metapackage. The reason seems to be, that the openssh-client package is corrupted. Redownloading / clearing the apt-get cache doesn't help.
Just installing the openssh-common and openssh-server packages is working fine.