CVE-2026-26973Discourse is an open source discussion platform.

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.

CVSS

4.3 MEDIUM (v3.1, NVD)CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

Weakness (CWE)

CWE-863, CWE-639

Known exploited

Not in CISA's KEV catalog

EPSS (exploitation in the next 30 days)

Not loaded for this CVE

Assigned by

Not given

NVD analysis

Analyzed

Record last updated

Jun 17, 2026

First seen by InfoSec Signals

Oct 9, 2026

The CVE record on cve.org · NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.