CVE-2026-27151: Discourse

Low severity, CVSS 2.7. EPSS: 0.3% chance of exploitation in the next 30 days.

Discourse is an open source discussion platform. Prior to versions 2025.12.2, 2026.1.1, and 2026.2.0, the `move_posts` action only checked `can_move_posts?` on the source topic but never validated write permissions on the destination topic. This allowed TL4 users and category group moderators to move posts into topics in categories where they lack posting privileges (e.g., read-only categories or categories with group-restricted write access). Versions 2025.12.2, 2026.1.1, and 2026.2.0 patch the issue. No known workarounds are available.

Affected products

• Discourse Discourse: before 2025.12.2 (fixed in 2025.12.2); from 2026.1.0, before 2026.1.1 (fixed in 2026.1.1); version 2026.2.0 only

Published 2026-02-26. Last modified 2026-06-17.