At Vienna airport, passengers connecting between two international flights can usually stay in the transit area without going through immigration.
The airport has 4 terminals or concourses (Gates B and C (Schengen), Gates F (Schengen, Terminal 3), Gates D (non-Schengen), Gates G (non-Schengen, Terminal 3)). All of them are connected after security, so you do not need to clear security again to change.