Discourse is an open-source discussion platform. From versions 2026.1.0 to before 2026.1.4, 2026.3.0 to before 2026.3.1, and 2026.4.0 to before 2026.4.1, DetailedTagSerializer#taggroupnames returned every tag group a tag belonged to without filtering against the requesting user's visibility. With SiteSetting.tagslistedbygroup enabled, anonymous and unprivileged users hitting TagsController#info (which is exempt from requireslogin) 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.
{
"cpes": [
"cpe:2.3:a:discourse:discourse:*:*:*:*:*:*:*:*"
],
"severity": "Medium"
}