Vulnerability Description
Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, requesting /posts/:id.json?version=X bypassed authorization checks on post revisions. The display_post method called post.revert_to directly without verifying whether the revision was hidden or if the user had permission to view edit history. This meant hidden revisions (intentionally concealed by staff) could be read by any user by simply enumerating version numbers. Starting in versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, Discourse looks up the PostRevision and call guardian.ensure_can_see! before reverting, consistent with how the /posts/:id/revisions/:revision endpoint already authorizes access. No known workarounds are available.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Discourse | Discourse | >= 2026.1.0, < 2026.1.2 |
Related Weaknesses (CWE)
References
- https://github.com/discourse/discourse/commit/8510fde30eb0d7f2dee822a95f6cf43b9aPatch
- https://github.com/discourse/discourse/commit/c0eeb5892f5d61ad62b057f4d468333a6ePatch
- https://github.com/discourse/discourse/commit/c474fbd79d2bd231baafb4332970297d78Patch
- https://github.com/discourse/discourse/security/advisories/GHSA-fq69-f929-wp96Vendor Advisory
FAQ
What is CVE-2026-27454?
CVE-2026-27454 is a vulnerability with a CVSS score of 5.3 (MEDIUM). Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, requesting /posts/:id.json?version=X bypassed authorization checks on post revisions. The ...
How severe is CVE-2026-27454?
CVE-2026-27454 has been rated MEDIUM with a CVSS base score of 5.3/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-27454?
Check the references section above for vendor advisories and patch information. Affected products include: Discourse Discourse.