Auth bypass in Discourse

CVE-2026-28227

Discourse is an open source discussion platform. Prior to versions 2025.12.2, 2026.1.1, and 2026.2.0, TL4 users can publish topics into staff-only categories via the `publish_to_category` topic timer, bypassing authorization checks. Versions 2025.12.2, 2026.1.1, and 2026.2.0 patch the issue. No known workarounds are available.

Vulnerability class: Broken Access Control

Published · last modified .

CVSS v3 metric

CVSS v3 base score 2.7 (Low). Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:N.

EPSS exploit prediction

EPSS: 0.003 (21.1th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 21st percentile — 21.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-28227: fell from 0.028 to 0.003.

EPSS over last 30 days · oldest: 0.028 · newest: 0.003 · change: -0.025

Affected products

  • Discourse — versions >= 2026.2.0-latest, < 2026.2.0, >= 2026.1.0-latest, < 2026.1.1, 2026.2.0

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-28227?
CVE-2026-28227 is a low-severity vulnerability in Discourse, classified under Incorrect Authorization. CVSS score: 2.7/10. Published 2026-02-26.
How severe is CVE-2026-28227?
Low severity. CVSS v3 base score is 2.7 out of 10.