All extensions in the Plesk Extensions Catalog,
whether published by Plesk, a Plesk partner, or a third party are
rigorously vetted and tested. You can always rely on them to be 100%
safe.
The only exception is the extensions in the “Beta” category
of the Extensions Catalog. Apart from Beta extensions, you must be careful with
extensions that come from sources other than the Plesk Extensions Catalog.
We recommend that you only install extensions from sources you trust.