However, my recollection is that by having UPnP enabled ends up being a security risk considering that you are basically allowing anything within your device to open ports directly into your firewall. If you end up having malware on it, then it can quickly spread to the remaining (vulnerable) devices in the network.
Unfortunately, I didn't pay enough attention to its consequences when I was running a node in the past until I read your comment and did some Googling... It appears that you're right
[it looks like I'll be sticking with outbound connections whenever I decide to run a node again (thank you)].
- For those who might be interested, here are two old threads (#1 and #2) with interesting arguments about it.