cross-posted from: https://sh.itjust.works/post/923025
lemmy.world is a victim of an XSS attack right now and the hacker simply injected a JavaScript redirection into the sidebar.
It appears the Lemmy backend does not escape HTML in the main sidebar. Not sure if this is also true for community sidebars.
That would essentially be patching the vulnerability. A temporary fix would be just preventing the sidebar from being editable.
(Ideally the vulnerability would be patched, but these things take time.)