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(URGENT) Lemmy has an XSS vulnerability in the sidebar (self.main)

submitted 2 years ago by AlternateRoute to c/main

41 comments fedilink hide all child comments

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.

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[–] tarjeezy 6 points 2 years ago (1 children)

Good luck, and thanks for all your hard work. I don't know if you already saw this, but it looks like this might be the vector for the account compromise. If that's the case, I don't think 2FA is enough to protect, because it's exfiltrating the session cookies of someone already logged in. Seems like the precaution is for admins to avoid clicking any suspicious links. I realize the irony of sharing a link about this, but at least it's to a thread on this instance.

https://lemmy.ca/post/1311411

[–] TruckBC 8 points 2 years ago

I'm copying all links into a brand new incognito mode window for now.