Auth bypass in Discourse
CVE-2026-45085
Discourse is an open-source discussion platform. From versions 2026.1.0-latest to before 2026.1.4, 2026.3.0-latest to before 2026.3.1, and 2026.4.0-latest to before 2026.4.1, four authorization/disclosure issues in the chat plugin (one also involving discourse-calendar): read-only category users could create chat threads, self-deleted chat messages could be restored by their author after channel access was revoked, moderators reviewing a flagged chat message were shown the channel's current last_message (often unrelated DM content), and calendar event payloads exposed the attached chat channel and its last message to viewers without chat access (including anonymous users). This affects sites with the chat plugin enabled; the calendar issue additionally requires discourse-calendar. This issue has been patched in versions 2026.1.4, 2026.3.1, 2026.4.1, and 2026.5.0-latest.1.
Vulnerability class: Information Disclosure
EPSS: 0.002 (11.6th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N.
Affected products
- Discourse — versions >= 2026.4.0-latest, < 2026.4.1, 2026.5.0, >= 2026.3.0-latest, < 2026.3.1
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Third Party Advisory)
Frequently asked questions
- What is CVE-2026-45085?
- CVE-2026-45085 is a medium-severity vulnerability in Discourse, classified under Information Disclosure. CVSS score: 5.3/10. Published 2026-06-12.
- How severe is CVE-2026-45085?
- Medium severity. CVSS v3 base score is 5.3 out of 10.