A number of Lemmy instances have been hacked overnight. Some may remain
inaccessible until they have been secured and restarted. As a safety precaution
logged-on sessions on many servers have been cancelled and you are required to
logon again. Unfortunately, the only way I could find to do this in L...
Drawing attention on this instance so Admins are aware and can address the propagating exploit.
If your instance has custom emojis defined, this is exploitable everywhere Markdown is available. It is NOT restricted to admins, but can be used to steal an admin's JWT, which then lets the attacker get into that admin's account which can then spread the exploit further by putting it somewhere where it's rendered on every single page and then deface the site.
If your instance doesn't have any custom emojis, you are safe, the exploit requires custom emojis to trigger the bad code branch.
I’m greatly surprised how Lemmy and the fediverse society has responded with this. The bug was found yesterday, maybe? And I’ve read about it three, four times (in different servers); a temporal solution was published in hours and it’s already patched on the repo.
Another victory for Open Source and the Fediverse in general.