Auth bypass in Discourse

CVE-2026-33424

Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, an attacker can grant access to a private message topic through invites even after they lose access to that PM. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch. No known workarounds are available.

Vulnerability class: Broken Access Control

Published · last modified .

CVSS v3 metric

CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:A/AC:H/PR:H/UI:R/S:U/C:H/I:H/A:L.

EPSS exploit prediction

EPSS: 0.003 (21.4th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 21st percentile — 21.4% 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-2026-33424: held from 0.002 to 0.003.

EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.001

Affected products

  • Discourse — versions = 2026.3.0-latest, >= 2026.2.0-latest, < 2026.2.1, >= 2026.1.0-latest, < 2026.1.2

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-33424?
CVE-2026-33424 is a medium-severity vulnerability in Discourse, classified under Incorrect Authorization. CVSS score: 5.9/10. Published 2026-03-21.
How severe is CVE-2026-33424?
Medium severity. CVSS v3 base score is 5.9 out of 10.