Discourse is an open source discussion platform. Prior to 3.2.3 and 3.3.0.beta3, improperly sanitized Onebox data could lead to an XSS vulnerability in some situations. This vulnerability only affects Discourse instances which have disabled the default Content Security Policy. This vulnerability is fixed in 3.2.3 and 3.3.0.beta3.
https://github.com/discourse/discourse/security/advisories/GHSA-cx83-5p6x-9qh9
https://github.com/discourse/discourse/commit/311b737c910cf0a69f61e1b8bc0b78374b6619d2
https://github.com/discourse/discourse/commit/26aef0c288839378b9de5819e96eac8cf4ea60fd