CVE-2026-27454
MediumDiscourse has check revision visibility on posts endpoint
Published Mar 19, 2026 · Updated Oct 6, 2026 · Also known as BIT-discourse-2026-27454, GHSA-fq69-f929-wp96
Key Facts
Routine patching- CVE-2026-27454 is a medium-severity vulnerability (CVSS 5.3 v3.1) affecting Discourse.
- It is not listed in any known-exploited vulnerabilities catalog. No public exploit code is known.
- EPSS estimates a 1.0% probability of exploitation in the next 30 days.
- Fixed versions are available, including Discourse 2026.1.2, Discourse 2026.2.1, Discourse 2026.3.0.
- Brandefense priority: routine patching, as no exploitation is known and its severity is moderate or low.
CVSS v3.1
5.3
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
EPSS (30-day exploit likelihood)
1.0%
Higher than 61.9% of all scored CVEs
Exploited in the wild
No known
Not in a known-exploited catalog
Public exploit code
None known
Get the full CVE-2026-27454 brief as a PDF
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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.
Affected Products
4 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| DiscourseDiscourse | 2026.3.0, >= 2026.1.0, >= >= 2026.1.0-latest, < 2026.1.2 | 2026.1.2 |
Patched Releases
Discourse
2026.1.2, 2026.2.1, 2026.3.0
Timeline
Publicly disclosed
Mar 19, 2026
Last updated
Oct 6, 2026
Weakness Type
- CWE-862 Missing Authorization
References
- advisoryhttps://github.com/CVEProject/cvelistV5/tree/main/cves/2026/27xxx/CVE-2026-27454.json
- articlehttps://nvd.nist.gov/vuln/detail/CVE-2026-27454
- otherhttps://github.com/discourse/discourse/commit/8510fde30eb0d7f2dee822a95f6cf43b9ac943d0
- otherhttps://github.com/discourse/discourse/commit/c0eeb5892f5d61ad62b057f4d468333a6e9f28c3
- otherhttps://github.com/discourse/discourse/commit/c474fbd79d2bd231baafb4332970297d781f92ca
FAQ
Common Questions.
Discourse is an open-source discussion platform.
Affected: Discourse versions 2026.3.0, >= 2026.1.0, >= >= 2026.1.0-latest, < 2026.1.2. The full list is in the CVE brief.
It is not listed in any known-exploited vulnerabilities catalog.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
No public exploit code is known.
Fixed versions are available, including Discourse 2026.1.2, Discourse 2026.2.1, Discourse 2026.3.0.
Brandefense priority: routine patching, as no exploitation is known and its severity is moderate or low.
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