Drawing attention on this instance so Admins are aware and can address the propagating exploit.
EDIT: Found more info about the patch.
A more thorough recap of the issue.
GitHub PR fixing the bug: https://github.com/LemmyNet/lemmy-ui/pull/1897/files
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.
Spreading FUD over a group of people’s intent with their software that they personally use is an odd take, when kbin could very well have similar vulnerabilities in its codebase. Federation is good as part of limiting the attack vector one of many implementations and a subset of all servers hosting and routing media content. Kbin is just another set of federated content servers, with there being no guarantee of who develops the software being inherently more competent than those who develop Lemmy.
