CVE-2026-21865

EUVD-2026-4874

28.01.2026, 20:16

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.

Provider	Type	Base Score	Atk. Vector	Atk. Complexity	Priv. Required	Vector
NIST	Primary	6.5 MEDIUM	NETWORK	LOW	HIGH	CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N
GitHub_M	CNA	6.5 MEDIUM	NETWORK	LOW	HIGH	CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N

Base Score

CVSS 3.x

EPSS Score

Percentile: 9%

Affected Products (NVD)

Vendor	Product	Version
discourse	discourse	𝑥 < 3.5.4
discourse	discourse	2025.11.0 ≤ 𝑥 < 2025.11.2
discourse	discourse	2025.12.0
discourse	discourse	2026.1.0

𝑥

= Vulnerable software versions

Common Weakness Enumeration

CWE-862 - Missing Authorization
The software does not perform an authorization check when an actor attempts to access a resource or perform an action.

References

https://github.com/discourse/discourse/security/advisories/GHSA-4777-wrv5-3g39