But in our particular case, only selected code from approved projects would
be submitted to the pool and just one master can submit jobs, which is our
center.
It sounds like it's not a wild west situation, but you have a fair amount
of control, and there is reason for users to trust you. So maybe it's not a
problem.
I'm afraid of vulnerabilities like IP-spoofing, DOS, buffer overflow, etc.
Condor has several methods for authorizing and authenticating connections.
This would help ensure that only certain people can submit jobs to the
pool. It adds complexity to the setup, but it's probably worth it. It would
help alleviate some of your concerns.
You can read about security in the manual. The manual description is a bit
opaque at times and needs to be updated, but you can figure out much of it
and ask questions for the parts you don't understand.