Description
Discourse is an open-source discussion platform. From versions 2026.1.0-latest to before 2026.1.4, 2026.3.0-latest to before 2026.3.1, and 2026.4.0-latest to before 2026.4.1, DetailedTagSerializer#tag_group_names returned every tag group a tag belonged to without filtering against the requesting user's visibility. With SiteSetting.tags_listed_by_group enabled, anonymous and unprivileged users hitting TagsController#info (which is exempt from requires_login) could read the names of tag groups restricted to specific user groups or non-visible categories. This issue has been patched in versions 2026.1.4, 2026.3.1, 2026.4.1, and 2026.5.0-latest.1.
Problem types
CWE-200: Exposure of Sensitive Information to an Unauthorized Actor
Product status
>= 2026.3.0-latest, < 2026.3.1
>= 2026.4.0-latest, < 2026.4.1
References
github.com/...course/security/advisories/GHSA-4q5q-6hh6-53x2