CVE-2026-45085
Discourse: Chat misauthorization and information disclosure
Description
Discourse is an open-source discussion platform. From versions 2026.1.0 to before 2026.1.4, 2026.3.0 to before 2026.3.1, and 2026.4.0 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users could create chat threads, self-deleted chat messages could be restored by their author after channel access was revoked, moderators reviewing a flagged chat message were shown the channel's current last_message (often unrelated DM content), and calendar event payloads exposed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.
How to fix CVE-2026-45085
To remediate CVE-2026-45085, upgrade the affected package to a fixed version below.
- —upgrade to 2026.1.4 or later
Is CVE-2026-45085 being exploited?
Low — EPSS is 0.2%, meaning exploitation activity has not been observed at scale.
Affected packages (1)
- >= 2026.1.0, < 2026.1.4, >= 2026.3.0, < 2026.3.1, >= 2026.4.0, < 2026.4.1
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | MEDIUM5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N |