Having worked with both open source and proprietary 3rd party software, in many ways, open source is actually maybe the safest pick. Or rather, proprietary stuff probably has the worst failure mode, where you end up being dependent on a legacy product with no support and no code(and this is pretty much guaranteed to happen at some point!). And even if there is support, it could take weeks to get a support request elevated to a bug report, assigned to a dev, reviewed, tested, yadda yadda yadda. Especially if you're a smaller customer.

I won't comment on overall risk of third party open source vs proprietary. But it is obviously true that open source has an advantage in that there's no problem that could arise that can't in principle be solved in-house.