CVE-2026-8428

HIGHNVD 8.88.8—
EchelonGraph scoreMEDIUM confidence

Score 8.8 from GitHub Security Advisory (severity: HIGH) published 2026-05-21. NVD baseline CVSS 8.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
8.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 8.8Exploit: 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 emits a CSRF token in the local_available_update.php view ($token->output('do_update')) but the corresponding do_update() method in concrete/controllers/single_page/dashboard/system/update/update.php never calls $this->token->validate('do_update'). The form is rendered as a POST form, meaning the token reaches the browser, but because the controller discards it without verification, an attacker can craft a cross-site POST that triggers a core CMS update to an attacker-specified version string.  In order to be vulnerable, theictim must be passing canUpgrade()anda valid update version must be present under DIR_CORE_UPDATES. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 7.5 with vector CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N. Thanks https://github.com/maru1009 for reporting.

CVSS v3
8.8
EG Score
8.8(medium)
EPSS
3.1%
KEV
Not listed

Published

May 21, 2026

Last Modified

May 26, 2026

Advisory Details (1)

Auto-updated Jun 2, 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-2026-8428(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(2)

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

Data Freshness Timeline

(refreshed 7× in last 7d / 57× 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.

Showing the most recent 100 of 122 total refreshes for this CVE.

  1. 2026-07-11 08:27 UTCEPSS rescore
  2. 2026-07-09 19:10 UTCEPSS rescore
  3. 2026-07-08 15:16 UTCEPSS rescore
  4. 2026-07-07 13:46 UTCEPSS rescore
  5. 2026-07-07 13:46 UTCEPSS rescore
  6. 2026-07-06 02:23 UTCEPSS rescore
  7. 2026-07-06 02:23 UTCEPSS rescore
  8. 2026-07-04 06:31 UTCEPSS rescore
  9. 2026-07-04 06:31 UTCEPSS rescore
  10. 2026-06-30 23:22 UTCEPSS rescore
  11. 2026-06-29 19:55 UTCEG score recompute
  12. 2026-06-29 14:06 UTCEPSS rescore
  13. 2026-06-28 14:07 UTCEPSS rescore
  14. 2026-06-28 10:47 UTCEG score recompute
  15. 2026-06-28 04:56 UTCEPSS rescore
  16. 2026-06-27 21:32 UTCEG score recompute
  17. 2026-06-27 08:25 UTCEG score recompute
  18. 2026-06-27 03:08 UTCEPSS rescore
  19. 2026-06-26 19:18 UTCEG score recompute
  20. 2026-06-26 03:25 UTCEG score recompute
  21. 2026-06-25 14:13 UTCEG score recompute
  22. 2026-06-25 13:50 UTCEPSS rescore
  23. 2026-06-24 14:05 UTCEPSS rescore
  24. 2026-06-23 21:33 UTCEPSS rescore
  25. 2026-06-22 14:25 UTCEPSS rescore
Show 75 more
  1. 2026-06-21 14:56 UTCEPSS rescore
  2. 2026-06-21 01:59 UTCEPSS rescore
  3. 2026-06-19 19:26 UTCEPSS rescore
  4. 2026-06-18 17:52 UTCEPSS rescore
  5. 2026-06-18 01:55 UTCEG score recompute
  6. 2026-06-18 01:55 UTCGHSA enrichment
  7. 2026-06-17 17:53 UTCEPSS rescore
  8. 2026-06-17 11:07 UTCEG score recompute
  9. 2026-06-17 11:07 UTCGHSA enrichment
  10. 2026-06-16 19:42 UTCEG score recompute
  11. 2026-06-16 19:42 UTCGHSA enrichment
  12. 2026-06-16 17:53 UTCEPSS rescore
  13. 2026-06-16 04:46 UTCEG score recompute
  14. 2026-06-16 04:46 UTCGHSA enrichment
  15. 2026-06-15 17:49 UTCEPSS rescore
  16. 2026-06-15 17:49 UTCEPSS rescore
  17. 2026-06-15 15:37 UTCEG score recompute
  18. 2026-06-15 15:37 UTCGHSA enrichment
  19. 2026-06-15 00:17 UTCEG score recompute
  20. 2026-06-15 00:17 UTCGHSA enrichment
  21. 2026-06-14 23:18 UTCEPSS rescore
  22. 2026-06-14 11:10 UTCEG score recompute
  23. 2026-06-14 11:09 UTCGHSA enrichment
  24. 2026-06-13 23:00 UTCEPSS rescore
  25. 2026-06-13 22:03 UTCEG score recompute
  26. 2026-06-13 22:03 UTCGHSA enrichment
  27. 2026-06-13 04:18 UTCEG score recompute
  28. 2026-06-13 04:18 UTCGHSA enrichment
  29. 2026-06-12 23:12 UTCEPSS rescore
  30. 2026-06-12 23:12 UTCEPSS rescore
  31. 2026-06-12 15:11 UTCEG score recompute
  32. 2026-06-12 15:10 UTCGHSA enrichment
  33. 2026-06-12 02:03 UTCEG score recompute
  34. 2026-06-12 02:03 UTCGHSA enrichment
  35. 2026-06-11 14:00 UTCEPSS rescore
  36. 2026-06-11 12:56 UTCEG score recompute
  37. 2026-06-11 12:56 UTCGHSA enrichment
  38. 2026-06-10 23:49 UTCEG score recompute
  39. 2026-06-10 23:49 UTCGHSA enrichment
  40. 2026-06-10 22:19 UTCEPSS rescore
  41. 2026-06-10 13:22 UTCEPSS rescore
  42. 2026-06-10 10:42 UTCEG score recompute
  43. 2026-06-10 10:42 UTCGHSA enrichment
  44. 2026-06-09 21:35 UTCEG score recompute
  45. 2026-06-09 21:35 UTCGHSA enrichment
  46. 2026-06-09 08:28 UTCEG score recompute
  47. 2026-06-09 08:28 UTCGHSA enrichment
  48. 2026-06-08 19:21 UTCEG score recompute
  49. 2026-06-08 19:21 UTCGHSA enrichment
  50. 2026-06-08 14:17 UTCEPSS rescore
  51. 2026-06-08 05:08 UTCEG score recompute
  52. 2026-06-08 05:08 UTCGHSA enrichment
  53. 2026-06-07 16:02 UTCEG score recompute
  54. 2026-06-07 16:02 UTCGHSA enrichment
  55. 2026-06-07 15:25 UTCEPSS rescore
  56. 2026-06-07 02:55 UTCEG score recompute
  57. 2026-06-07 02:55 UTCGHSA enrichment
  58. 2026-06-06 13:48 UTCEG score recompute
  59. 2026-06-06 13:48 UTCGHSA enrichment
  60. 2026-06-06 13:47 UTCEPSS rescore
  61. 2026-06-06 00:41 UTCEG score recompute
  62. 2026-06-06 00:41 UTCGHSA enrichment
  63. 2026-06-05 22:47 UTCEPSS rescore
  64. 2026-06-05 11:35 UTCEG score recompute
  65. 2026-06-05 11:35 UTCGHSA enrichment
  66. 2026-06-05 06:10 UTCEPSS rescore
  67. 2026-06-04 22:26 UTCEG score recompute
  68. 2026-06-04 22:26 UTCGHSA enrichment
  69. 2026-06-04 13:12 UTCEPSS rescore
  70. 2026-06-04 09:19 UTCEG score recompute
  71. 2026-06-04 09:19 UTCGHSA enrichment
  72. 2026-06-03 20:12 UTCEG score recompute
  73. 2026-06-03 20:12 UTCGHSA enrichment
  74. 2026-06-03 07:05 UTCEG score recompute
  75. 2026-06-03 07:05 UTCGHSA enrichment

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-8428?
CVE-2026-8428 is a high vulnerability published on May 21, 2026. Concrete CMS 9.5.0 and below emits a CSRF token in the localavailableupdate.php view ($token->output('doupdate')) but the corresponding doupdate() method in concrete/controllers/singlepage/dashboard/system/update/update.php never calls $this->token->validate('doupdate'). The form is rendered as a…
When was CVE-2026-8428 disclosed?
CVE-2026-8428 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-2026-8428 actively exploited?
CVE-2026-8428 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 3.1% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-8428?
CVE-2026-8428 has a CVSS v3 base score of 8.8 (NVD).
How do I remediate CVE-2026-8428?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-8428, 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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