CVE-2026-27454

MEDIUMPre-NVD 5.35.3—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.5%, top 62% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Elevated
5.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 5.3Exploit: Elevated riskExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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 v3
5.3
EG Score
5.3(medium)
EG Risk
29(Track)
EG Risk 29/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity53% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
58%
KEV
Not listed

Published

March 19, 2026

Last Modified

June 17, 2026

Advisory Details (4)

Auto-updated Aug 6, 2026
Patch available. Sources: github_commit, github.
github Patch Available

Check revision visibility on posts endpoint · Advisory · discourse/discourse · GitHub

https://github.com/discourse/discourse/security/advisories/GHSA-fq69-f929-wp96
github_commit

commit c474fbd79d2b (discourse/discourse)

Fix landed in discourse/discourse commit c474fbd79d2b — awaiting tagged release

https://github.com/discourse/discourse/commit/c474fbd79d2bd231baafb4332970297d781f92ca
github_commit Patch Available

commit c0eeb5892f5d (discourse/discourse)

Patch available: discourse/discourse _gh-attach-assets (contains commit c0eeb5892f5d)

https://github.com/discourse/discourse/commit/c0eeb5892f5d61ad62b057f4d468333a6e9f28c3
github_commit

commit 8510fde30eb0 (discourse/discourse)

Fix landed in discourse/discourse commit 8510fde30eb0 — awaiting tagged release

https://github.com/discourse/discourse/commit/8510fde30eb0d7f2dee822a95f6cf43b9ac943d0

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 6× in last 7d / 26× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-09-18 19:28 UTCEPSS rescore
  2. 2026-09-18 19:27 UTCEPSS rescore
  3. 2026-09-17 19:30 UTCEPSS rescore
  4. 2026-09-16 14:08 UTCEPSS rescore
  5. 2026-09-16 05:15 UTCEPSS rescore
  6. 2026-09-13 16:47 UTCEPSS rescore
  7. 2026-09-12 15:01 UTCEPSS rescore
  8. 2026-09-11 14:52 UTCEPSS rescore
  9. 2026-09-10 09:34 UTCEPSS rescore
  10. 2026-09-08 22:00 UTCEPSS rescore
  11. 2026-09-07 16:01 UTCEPSS rescore
  12. 2026-09-06 13:47 UTCEPSS rescore
  13. 2026-09-06 13:47 UTCEPSS rescore
  14. 2026-09-04 05:06 UTCEPSS rescore
  15. 2026-09-02 17:38 UTCOSV refresh
  16. 2026-09-02 14:11 UTCEPSS rescore
  17. 2026-09-01 13:53 UTCEPSS rescore
  18. 2026-09-01 04:39 UTCEPSS rescore
  19. 2026-08-30 19:17 UTCEPSS rescore
  20. 2026-08-30 01:22 UTCEPSS rescore
  21. 2026-08-28 21:41 UTCEPSS rescore
  22. 2026-08-27 14:25 UTCEPSS rescore
  23. 2026-08-26 14:46 UTCEPSS rescore
  24. 2026-08-25 13:48 UTCEPSS rescore
  25. 2026-08-23 00:19 UTCEPSS rescore
Show 35 more
  1. 2026-08-21 23:49 UTCEPSS rescore
  2. 2026-08-20 22:55 UTCEPSS rescore
  3. 2026-08-19 17:03 UTCEPSS rescore
  4. 2026-08-18 13:48 UTCEPSS rescore
  5. 2026-08-17 13:47 UTCEPSS rescore
  6. 2026-08-16 14:56 UTCEPSS rescore
  7. 2026-08-16 11:09 UTCEG score recompute
  8. 2026-08-16 02:14 UTCEPSS rescore
  9. 2026-08-15 01:30 UTCEPSS rescore
  10. 2026-08-14 07:19 UTCEG score recompute
  11. 2026-08-13 22:00 UTCEPSS rescore
  12. 2026-08-12 23:48 UTCEG score recompute
  13. 2026-08-12 13:50 UTCEPSS rescore
  14. 2026-08-11 21:28 UTCEG score recompute
  15. 2026-08-11 13:42 UTCEPSS rescore
  16. 2026-08-11 00:00 UTCEPSS rescore
  17. 2026-08-10 09:15 UTCEG score recompute
  18. 2026-08-09 13:46 UTCEPSS rescore
  19. 2026-08-09 06:53 UTCEG score recompute
  20. 2026-08-08 16:37 UTCEPSS rescore
  21. 2026-08-07 17:22 UTCEG score recompute
  22. 2026-08-06 13:46 UTCEPSS rescore
  23. 2026-08-06 01:33 UTCEG score recompute
  24. 2026-08-05 19:17 UTCEPSS rescore
  25. 2026-08-04 15:10 UTCEPSS rescore
  26. 2026-08-04 00:41 UTCEG score recompute
  27. 2026-08-03 10:36 UTCEPSS rescore
  28. 2026-08-02 16:33 UTCEG score recompute
  29. 2026-08-02 02:26 UTCEPSS rescore
  30. 2026-08-01 04:16 UTCEPSS rescore
  31. 2026-07-30 16:27 UTCEPSS rescore
  32. 2026-07-30 01:30 UTCEPSS rescore
  33. 2026-07-28 15:36 UTCEPSS rescore
  34. 2026-07-27 14:38 UTCEG score recompute
  35. 2026-07-27 14:27 UTCOSV refresh

Publicly available exploits

(1 reference)

Working exploit code is in the public domain. Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • Nucleihttp/cves/2026/CVE-2026-27454.yaml
    First seen Jan 1, 2026

    Discourse <=2026.2.0 - Hidden Post Revision Disclosure via revert_to Authorization Bypass

    Open source ↗

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-27454?
CVE-2026-27454 is a medium vulnerability published on March 19, 2026. 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 displaypost method called post.revertto directly without verifying whether the revision was hidden…
When was CVE-2026-27454 disclosed?
CVE-2026-27454 was first published in the National Vulnerability Database on March 19, 2026, with the most recent update on June 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-27454 actively exploited?
CVE-2026-27454 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 42.1% of all scored CVEs.
What is the CVSS score of CVE-2026-27454?
CVE-2026-27454 has a CVSS v3 base score of 5.3 (NVD).
How do I remediate CVE-2026-27454?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-27454, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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