CVE-2026-21865
Medium
Description
Discourse is an open source discussion platform. In versions prior to 3.5.4, 2025.11.2, 2025.12.1, and 2026.1.0, moderators can convert some personal messages to public topics when they shouldn't have access. This issue is patched in versions 3.5.4, 2025.11.2, 2025.12.1, and 2026.1.0. As a workaround, site admin can temporarily revoke the moderation role from untrusted moderators or remove the moderator group from the "personal message enabled groups" site setting until the Discourse instance has been upgraded to a version that has been patched.
SeverityMedium
CVSS6.5
Exploit probability—
Product
Discourse
PublishedJan 28, 2026
First seenJan 28, 2026
Weakness typeCWE-862Missing authorization
How to fix
Update
- discourse discourse3.5.4, 2025.11.2 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| discourse discourse | v < 3.5.4, 2025.11.0 ≤ v < 2025.11.2, 2025.12.0, 2026.1.0 | 3.5.4, 2025.11.2 |
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