Medium severity · published Jan 28, 2026
CVE-2026-21865
Discourse topic conversion permission vulnerability for moderators
6.5
CVSS
0.3%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N
Attack vector
Network
Complexity
Low
Privileges
High
User interaction
None
Confidentiality
High
Integrity
High
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 18% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
DI
discourse · discourse
< 3.5.4; >= 2025.11.0-latest, < 2025.11.2; >= 2025.12.0-latest, < 2025.12.1; >= 2026.1.0-latest, < 2026.1.0 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-21865
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-21865
Third Party Advisory
https://github.com/discourse/discourse/security/advisories/GHSA-4777-wrv5-3g39
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