The terms "Erratum/Errata" may be misleading for those who are not familiar with the way how Linux repositories are working.
Basically every Erratum will add newer packages to the Repository at updates.software-univention.de .
If you run "apt-get upgrade" - which is the base-technology in the background - the new packages are detected, downloaded and installed.
There are some more or less usable methods to block packages ot to downgrade (some examples in How to Downgrade a Package via apt-get?).
You can see the package(s) in question in the description of every Erratum.