Safe as long as the trolls don't have space internet access
They do have a space internet running, with TCP/IP optimized for the crazy long round trip times, but it's safe as long as the Chinese, Iranian, Russians, Norks, 4channers, or other purely malicious trolls can't get at it. China might not bother since there's not much IP they could gain from hacking Ingenuity, but Russia would do it from pure spite since destroying nice things (like the ISS) is all they can do now.
Of course someone's computer at JWP is probably on both Worst Internet (our normal internet) and Space Internet, so I sure hope they have things firewalled well and there's nowhere for the jndi query to go.
At least the rover is running VxWorks, so that's pretty solid.