Discourse-reactions is a plugin that allows user to add their reactions to the post in the Discourse messaging platform. In affected versions data about what reactions were performed on a post in a private topic could be leaked. This issue has been addressed in version 0.3. Users are advised to upgrade. Users unable to upgrade should disable the discourse-reactions plugin to fully mitigate the issue.
https://github.com/discourse/discourse-reactions/security/advisories/GHSA-4cgc-c7vh-94g6
https://github.com/discourse/discourse-reactions/commit/01aca15b2774c088f3673118e92e9469f37d2fb6