CVE-2026-8239

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/get_rating' endpoint confirms existence and returns rating score for any message by ID. 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 Tristan Madani for reporting.

CVSS v3
5.3
EG Score
5.3(medium)
EPSS
9.3%
KEV
Not listed

Published

May 21, 2026

Last Modified

May 26, 2026

Advisory Details (1)

Auto-updated Jun 14, 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-2026-8239(1)

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

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 75 more
  1. 2026-06-27 20:19 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. 2026-06-18 01:55 UTCEG score recompute
  14. 2026-06-18 01:55 UTCGHSA enrichment
  15. 2026-06-16 23:49 UTCEG score recompute
  16. 2026-06-16 23:49 UTCGHSA enrichment
  17. 2026-06-16 17:53 UTCEPSS rescore
  18. 2026-06-15 22:47 UTCEG score recompute
  19. 2026-06-15 22:46 UTCGHSA enrichment
  20. 2026-06-15 17:49 UTCEPSS rescore
  21. 2026-06-15 17:49 UTCEPSS rescore
  22. 2026-06-14 23:18 UTCEPSS rescore
  23. 2026-06-14 16:18 UTCEG score recompute
  24. 2026-06-14 16:18 UTCGHSA enrichment
  25. 2026-06-13 23:00 UTCEPSS rescore
  26. 2026-06-13 15:09 UTCEG score recompute
  27. 2026-06-13 15:09 UTCGHSA enrichment
  28. 2026-06-12 23:12 UTCEPSS rescore
  29. 2026-06-12 23:12 UTCEPSS rescore
  30. 2026-06-12 14:06 UTCEG score recompute
  31. 2026-06-12 14:06 UTCGHSA enrichment
  32. 2026-06-11 14:00 UTCEPSS rescore
  33. 2026-06-11 13:03 UTCEG score recompute
  34. 2026-06-11 13:03 UTCGHSA enrichment
  35. 2026-06-10 22:19 UTCEPSS rescore
  36. 2026-06-10 13:22 UTCEPSS rescore
  37. 2026-06-10 12:00 UTCEG score recompute
  38. 2026-06-10 12:00 UTCGHSA enrichment
  39. 2026-06-09 10:57 UTCEG score recompute
  40. 2026-06-09 10:57 UTCGHSA enrichment
  41. 2026-06-08 14:17 UTCEPSS rescore
  42. 2026-06-08 09:55 UTCEG score recompute
  43. 2026-06-08 09:55 UTCGHSA enrichment
  44. 2026-06-07 15:25 UTCEPSS rescore
  45. 2026-06-07 08:52 UTCEG score recompute
  46. 2026-06-07 08:52 UTCGHSA enrichment
  47. 2026-06-06 13:47 UTCEPSS rescore
  48. 2026-06-06 07:50 UTCEG score recompute
  49. 2026-06-06 07:50 UTCGHSA enrichment
  50. 2026-06-05 22:47 UTCEPSS rescore
  51. 2026-06-05 06:47 UTCEG score recompute
  52. 2026-06-05 06:47 UTCGHSA enrichment
  53. 2026-06-05 06:10 UTCEPSS rescore
  54. 2026-06-04 13:12 UTCEPSS rescore
  55. 2026-06-04 05:44 UTCEG score recompute
  56. 2026-06-04 05:44 UTCGHSA enrichment
  57. 2026-06-03 04:41 UTCEG score recompute
  58. 2026-06-03 04:41 UTCGHSA enrichment
  59. 2026-06-02 20:13 UTCEPSS rescore
  60. 2026-06-02 03:38 UTCEG score recompute
  61. 2026-06-02 03:38 UTCGHSA enrichment
  62. 2026-06-01 13:52 UTCEPSS rescore
  63. 2026-06-01 02:35 UTCEG score recompute▼ 1.00
  64. 2026-06-01 02:35 UTCGHSA enrichment
  65. 2026-05-31 22:30 UTCEPSS rescore
  66. 2026-05-31 00:16 UTCEPSS rescore
  67. 2026-05-29 13:44 UTCEPSS rescore
  68. 2026-05-28 13:44 UTCEPSS rescore
  69. 2026-05-27 13:40 UTCEPSS rescore
  70. 2026-05-27 13:40 UTCEPSS rescore
  71. 2026-05-26 13:44 UTCEPSS rescore
  72. 2026-05-26 07:18 UTCEPSS rescore
  73. 2026-05-23 00:07 UTCEG score recompute
  74. 2026-05-22 22:08 UTCEG score recompute
  75. 2026-05-21 22:44 UTCEG score recompute

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-8239?
CVE-2026-8239 is a medium vulnerability published on May 21, 2026. Concrete CMS 9.5.0 and below is vulnerable to IDOR. The '/ccm/frontend/conversations/get_rating' endpoint confirms existence and returns rating score for any message by ID. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 6.3 with Vector…
When was CVE-2026-8239 disclosed?
CVE-2026-8239 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-2026-8239 actively exploited?
CVE-2026-8239 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 9.3% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-8239?
CVE-2026-8239 has a CVSS v3 base score of 5.3 (NVD).
How do I remediate CVE-2026-8239?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-8239, 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.

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