This issue is already quite widely publicized and quite frankly “we’re handling it and removing this” is a much more harmful response than I would hope to see. Especially as the admins of that instance have not yet upgraded the frontend version to apply the urgent fix.
It’s not like this was a confidential bug fix, this is a zero day being actively exploited. Please be more cooperative and open regarding these issues in your own administration if you’re hosting an instance. 🙏
From what I found digging through some posts, this exploit only works if your instance uses custom emoji. Federated custom emoji are apparently harmless.
Yes, if you have no custom emoji on your instance, you should not be vulnerable. A valid workaround before the fix is also to just remove all custom emoji, from what I’ve also read.