CVE-2026-27151

Discourse doesn't validate destination topic when moving posts

State: Published
Severity: 1.3 Low
Published: Feb 26, 2026
Updated: Mar 3, 2026
Reserved: Feb 18, 2026

Description

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.

Scores

CVSS	Score	Vector	Source
4.0	1.3 Low	CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U	GitHub_M

Weaknesses

CWE-862 Missing Authorization

Affected Products

Product	Versions
discoursediscourse	< 2025.12.2Affected >= 2026.1.0-latest, < 2026.1.1Affected >= 2026.2.0-latest, < 2026.2.0Affected

References

https://github.com/discourse/discourse/security/advisories/GHSA-m69h-9m2g-cfgw

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