CVE-2026-21865 json
Discourse topic conversion permission vulnerability for moderators
published 2026-01-28 9 mo ago modified 2026-09-08 2 mo ago also BIT-discourse-2026-21865 , EUVD-2026-4874 , GHSA-4777-wrv5-3g39
- cvss
- 6.5
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.3%
- EPSS 0.3% chance of exploitation in 30 days, percentile 18%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- bitnami discourse 3.5.4, 2025.11.2, 2025.12.1, 2026.1.0
- discourse discourse 3.5.4, 2025.11.2, 2025.12.1, 2026.1.0
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- 9 mo ago
Exploit prediction
0.26% chance of exploitation in the next 30 days, higher than 18% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 6.5 | CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N |
| OSV | 3.1 | 6.5 | CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| bitnami | discourse | <3.5.4 >=2025.11.0, <2025.11.2 >=2025.12.0, <2025.12.1 >=2026.1.0, <2026.1.0 |
3.5.4 2025.11.2 2025.12.1 2026.1.0 |
Affected products
- discourse discourse
Classification
- Weakness
-
- CWE-862 Missing Authorization
References
-
github.com
/discourse/discourse/security/advisories/GHSA-4777-wrv5-3g39
third-party-advisory, advisory
-
nvd.nist.gov
/vuln/detail/CVE-2026-21865
web
Sources
- CVE List CVE-2026-21865
- NVD CVE-2026-21865
- OSV BIT-discourse-2026-21865
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.
CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.