Last night, several Lemmy instances (including lemmy.world) were breached and defaced. More details can be found here: https://lemmy.ml/post/1901079
This breach only affected instances that had custom emoji configured. I hadn't gotten to setting those up yet here, so this instance should not be vulnerable.
0.18.2 upgrade is complete without any issues. Several other bugs I've seen around have also been fixed. It's great to see Lemmy development progressing so quickly!