VulnerabilityAnalyzed

CVE-2026-27151

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).

LOW 1.3EPSS 0.15%

Does this matter?

Lower severity and a low EPSS score (0.15%). Track it; it rarely justifies an emergency change on its own.

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.

CVSS 4.0: 1.3 LOWCVSS: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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
EPSS: 0.15% probability · 5th percentile
CISA KEV: Not listed
Weakness: CWE-862
Affected: discourse/discourse
Source: security-advisories@github.com

References

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

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.