🛡️ CVE-2026-27454 — discourse

🟡 CVSS 5.0 — Medium ✅ No Known Exploit CWE-862 OSV
5.0
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

Discourse has check revision visibility on posts endpoint

Discourse is an open-source discussion platform. Prior to versions 2026.3.0, 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, 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.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality low, integrity none, availability none.

Weakness class

CVE-2026-27454 is classified as CWE-862: Missing Authorization. No authorisation check is performed before carrying out a restricted action.

Affected software

CVE-2026-27454 is recorded against 1 package.

  • discourse

Timeline and source

Published on 27 March 2026 and last revised on 17 June 2026. No public exploit is currently recorded for this entry. A vendor advisory or fix has been published. Record sourced from OSV.

References

github.com (Web)
github.com (Web)
github.com (Web)
github.com (Web)
nvd.nist.gov (Web)

Details

Severity MEDIUM
CVSS Score 5.0
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
CWE CWE-862
Public Exploit ✅ No
Source OSV
Published 2026-03-27
Updated 2026-08-12
Modified 2026-06-17

Affected Packages

Software From version Fixed in
discourse — —

Similar Threats

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