CVE-2026-27454 (GCVE-0-2026-27454)
Vulnerability from cvelistv5 – Published: 2026-03-19 20:39 – Updated: 2026-03-20 17:10
VLAI
EPSS
VEX
Title
Discourse has check revision visibility on posts endpoint
Summary
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.
Severity
5.3 (Medium)
SSVC
Exploitation: none
Automatable: yes
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-03-20 17:10 UTC
CWE
- CWE-862 - Missing Authorization
Assigner
GitHub_M
CNA
References
4 references
| URL | Tags |
|---|---|
| https://github.com/discourse/discourse/security/a… | x_refsource_CONFIRM |
| https://github.com/discourse/discourse/commit/851… | x_refsource_MISC |
| https://github.com/discourse/discourse/commit/c0e… | x_refsource_MISC |
| https://github.com/discourse/discourse/commit/c47… | x_refsource_MISC |
Impacted products
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"title": "CISA ADP Vulnrichment"
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}
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The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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