{"id":"BIT-discourse-2026-26973","summary":"Discourse doesn't scope reviewable notes to user-visible reviewables","details":"Discourse is an open source discussion platform. Versions prior to 2025.12.2, 2026.1.1, and 2026.2.0 have an IDOR (Insecure Direct Object Reference) in `ReviewableNotesController`. When `enable_category_group_moderation` is enabled, a user belonging to a  category moderation group can create or delete their own notes on **any** reviewable in the system, including reviewables in categories they do not moderate. The controller used an unscoped `Reviewable.find` and the `ensure_can_see` guard only checked whether the user could access the review queue in general, not whether they could access the specific reviewable. Only instances with `enable_category_group_moderation` enabled are affected. Staff users (admins/moderators) are not impacted as they already have access to all reviewables. The issue is patched in versions 2025.12.2, 2026.1.1, and 2026.2.0 by scoping the reviewable lookup through `Reviewable.viewable_by(current_user)`. As a workaround, disable the `enable_category_group_moderation` site setting. This removes the attack surface as only staff users will have access to the review queue.","aliases":["CVE-2026-26973","GHSA-c587-qx78-vhmx"],"modified":"2026-09-08T08:46:20.792118043Z","published":"2026-03-03T13:29:10.861Z","database_specific":{"cpes":["cpe:2.3:a:discourse:discourse:*:*:*:*:*:*:*:*"],"severity":"Medium"},"references":[{"type":"ADVISORY","url":"https://github.com/discourse/discourse/security/advisories/GHSA-c587-qx78-vhmx"},{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-26973"}],"affected":[{"package":{"name":"discourse","ecosystem":"Bitnami","purl":"pkg:bitnami/discourse"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"2025.12.2"},{"introduced":"2026.1.0"},{"fixed":"2026.1.1"}]}],"database_specific":{"source":"https://github.com/bitnami/vulndb/tree/main/data/discourse/BIT-discourse-2026-26973.json"},"severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N"}]}],"schema_version":"1.9.0"}