CVE-2026-8237

MEDIUMNVD 5.35.3—
EchelonGraph scoreMEDIUM confidence

Score 5.3 from GitHub Security Advisory published 2026-05-22. NVD baseline CVSS 5.3; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
5.3
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 5.3Exploit: NoneExposed: 0

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

Concrete CMS 9.5.0 and below is vulnerable to IDOR. The /ccm/frontend/conversations/message_detail endpoint returns the full content of any conversation message. An unauthenticated attacker can enumerate all conversation messages, including messages from restricted pages, member-only areas, and the moderation queue. File attachments with download URLs are also exposed. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 6.3 with Vector CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N. Thanks Eldudareeno for reporting.

CVSS v3
5.3
EG Score
5.3(medium)
EPSS
10.1%
KEV
Not listed

Published

May 21, 2026

Last Modified

May 26, 2026

Advisory Details (1)

Auto-updated Jun 15, 2026
No patch confirmed yet.
generic

9.5.1 Release Notes :: Concrete CMS

https://documentation.concretecms.org/9-x/developers/introduction/version-history/951-release-notes

Vendor Advisories for CVE-2026-8237(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(1 across 1 ecosystem)
Packagist(1)
PackageVulnerable rangeFixed inDependents
concrete5/concrete58.0 ... 9.5.0RC2 (89 versions)9.5.1—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 7× in last 7d / 42× 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. 2026-07-15 16:57 UTCEPSS rescore
  2. 2026-07-15 02:00 UTCEPSS rescore
  3. 2026-07-13 22:31 UTCEPSS rescore
  4. 2026-07-13 06:13 UTCEPSS rescore
  5. 2026-07-12 05:46 UTCEPSS rescore
  6. 2026-07-11 08:27 UTCEPSS rescore
  7. 2026-07-09 19:10 UTCEPSS rescore
  8. 2026-07-08 15:16 UTCEPSS rescore
  9. 2026-07-08 15:16 UTCEPSS rescore
  10. 2026-07-07 13:46 UTCEPSS rescore
  11. 2026-07-07 13:46 UTCEPSS rescore
  12. 2026-07-06 16:27 UTCEPSS rescore
  13. 2026-07-06 16:27 UTCEPSS rescore
  14. 2026-07-06 02:23 UTCEPSS rescore
  15. 2026-07-06 02:23 UTCEPSS rescore
  16. 2026-07-05 02:31 UTCEPSS rescore
  17. 2026-07-05 02:30 UTCEPSS rescore
  18. 2026-07-04 06:31 UTCEPSS rescore
  19. 2026-07-04 06:31 UTCEPSS rescore
  20. 2026-07-01 15:07 UTCEPSS rescore
  21. 2026-06-30 23:22 UTCEPSS rescore
  22. 2026-06-29 19:54 UTCEG score recompute
  23. 2026-06-29 14:06 UTCEPSS rescore
  24. 2026-06-28 14:07 UTCEPSS rescore
  25. 2026-06-28 04:56 UTCEPSS rescore
Show 73 more
  1. 2026-06-27 21:23 UTCEG score recompute
  2. 2026-06-27 03:08 UTCEPSS rescore
  3. 2026-06-26 19:17 UTCEG score recompute
  4. 2026-06-25 14:12 UTCEG score recompute
  5. 2026-06-25 13:50 UTCEPSS rescore
  6. 2026-06-24 14:05 UTCEPSS rescore
  7. 2026-06-23 21:33 UTCEPSS rescore
  8. 2026-06-22 14:25 UTCEPSS rescore
  9. 2026-06-21 14:56 UTCEPSS rescore
  10. 2026-06-21 01:59 UTCEPSS rescore
  11. 2026-06-19 19:26 UTCEPSS rescore
  12. 2026-06-18 17:52 UTCEPSS rescore
  13. 2026-06-17 12:44 UTCEG score recompute
  14. 2026-06-17 12:44 UTCGHSA enrichment
  15. 2026-06-16 17:53 UTCEPSS rescore
  16. 2026-06-16 10:33 UTCEG score recompute
  17. 2026-06-16 10:33 UTCGHSA enrichment
  18. 2026-06-15 17:49 UTCEPSS rescore
  19. 2026-06-15 17:49 UTCEPSS rescore
  20. 2026-06-15 08:08 UTCEG score recompute
  21. 2026-06-15 08:08 UTCGHSA enrichment
  22. 2026-06-14 23:18 UTCEPSS rescore
  23. 2026-06-14 06:02 UTCEG score recompute
  24. 2026-06-14 06:02 UTCGHSA enrichment
  25. 2026-06-13 23:00 UTCEPSS rescore
  26. 2026-06-13 03:47 UTCEG score recompute
  27. 2026-06-13 03:47 UTCGHSA enrichment
  28. 2026-06-12 23:12 UTCEPSS rescore
  29. 2026-06-12 23:12 UTCEPSS rescore
  30. 2026-06-12 01:39 UTCEG score recompute
  31. 2026-06-12 01:39 UTCGHSA enrichment
  32. 2026-06-11 14:00 UTCEPSS rescore
  33. 2026-06-10 23:33 UTCEG score recompute
  34. 2026-06-10 23:33 UTCGHSA enrichment
  35. 2026-06-10 22:19 UTCEPSS rescore
  36. 2026-06-10 13:22 UTCEPSS rescore
  37. 2026-06-09 21:28 UTCEG score recompute
  38. 2026-06-09 21:28 UTCGHSA enrichment
  39. 2026-06-08 19:21 UTCEG score recompute
  40. 2026-06-08 19:21 UTCGHSA enrichment
  41. 2026-06-08 14:17 UTCEPSS rescore
  42. 2026-06-07 15:25 UTCEPSS rescore
  43. 2026-06-07 15:11 UTCEG score recompute
  44. 2026-06-07 15:11 UTCGHSA enrichment
  45. 2026-06-06 13:47 UTCEPSS rescore
  46. 2026-06-06 13:05 UTCEG score recompute
  47. 2026-06-06 13:05 UTCGHSA enrichment
  48. 2026-06-05 22:47 UTCEPSS rescore
  49. 2026-06-05 10:59 UTCEG score recompute
  50. 2026-06-05 10:59 UTCGHSA enrichment
  51. 2026-06-05 06:10 UTCEPSS rescore
  52. 2026-06-04 13:12 UTCEPSS rescore
  53. 2026-06-04 08:53 UTCEG score recompute
  54. 2026-06-04 08:53 UTCGHSA enrichment
  55. 2026-06-03 06:47 UTCEG score recompute
  56. 2026-06-03 06:47 UTCGHSA enrichment
  57. 2026-06-02 20:13 UTCEPSS rescore
  58. 2026-06-02 04:41 UTCEG score recompute
  59. 2026-06-02 04:41 UTCGHSA enrichment
  60. 2026-06-01 13:52 UTCEPSS rescore
  61. 2026-06-01 02:35 UTCEG score recompute▼ 1.00
  62. 2026-06-01 02:35 UTCGHSA enrichment
  63. 2026-05-31 22:30 UTCEPSS rescore
  64. 2026-05-31 00:16 UTCEPSS rescore
  65. 2026-05-29 13:44 UTCEPSS rescore
  66. 2026-05-28 13:44 UTCEPSS rescore
  67. 2026-05-27 13:40 UTCEPSS rescore
  68. 2026-05-27 13:40 UTCEPSS rescore
  69. 2026-05-26 13:44 UTCEPSS rescore
  70. 2026-05-26 07:18 UTCEPSS rescore
  71. 2026-05-23 00:07 UTCEG score recompute
  72. 2026-05-22 22:08 UTCEG score recompute
  73. 2026-05-21 22:44 UTCEG score recompute

Frequently asked(5)

What is CVE-2026-8237?
CVE-2026-8237 is a medium vulnerability published on May 21, 2026. Concrete CMS 9.5.0 and below is vulnerable to IDOR. The /ccm/frontend/conversations/message_detail endpoint returns the full content of any conversation message. An unauthenticated attacker can enumerate all conversation messages, including messages from restricted pages, member-only areas, and the…
When was CVE-2026-8237 disclosed?
CVE-2026-8237 was first published in the National Vulnerability Database on May 21, 2026, with the most recent update on May 26, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-8237 actively exploited?
CVE-2026-8237 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 10.1% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-8237?
CVE-2026-8237 has a CVSS v3 base score of 5.3 (NVD).
How do I remediate CVE-2026-8237?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-8237, 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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