CVE-2026-26973 (GCVE-0-2026-26973)

Vulnerability from cvelistv5 – Published: 2026-02-26 19:19 – Updated: 2026-02-26 20:41
VLAI
Title
Discourse doesn't scope reviewable notes to user-visible reviewables
Summary
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.
Severity
4.3 (Medium)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-02-26 20:40 UTC
CWE
  • CWE-863 - Incorrect Authorization
Assigner
GitHub_M CNA under the mitre root
CNA scorecard C 72/100 over 7812 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
discourse discourse Affected: < 2025.12.2
Affected: >= 2026.1.0-latest, < 2026.1.1
Affected: >= 2026.2.0-latest, < 2026.2.0
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

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