CVE-2026-8205 - Concrete CMS 9.5.0 and below is vulnerable to authorization bypass in Calendar Block since action_get_events does not check canView on the calendar

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MEDIUM

Concrete CMS 9.5.0 and below is vulnerable to authorization bypass in Calendar Block since action_get_events does not check canView on the calendar

Published May 21, 2026

6.3

MEDIUM

CVSS 4.0

EPSS 0.35%

Description

Concrete CMS 9.5.0 and below is vulnerable to authorization bypass in the Calendar Block since action_get_events does not check canView on the calendar which results in restricted event details being disclosed. 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 lalalala5678 for reporting.

Affected products

Vendor Concrete CMS Product Concrete CMS Default
unaffected
- Version
  5.0
  Status
  affected
  Constraints
  <=9.5.0

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor

Product

Default status

Versions

Concrete CMS

unaffected

Version	Status	Constraints
5.0	affected	<=9.5.0

Remediation

No remediation recorded yet.

Weaknesses (1)

CWE-425

References (4)

https://documentation.concretecms.org/9-x/developers/introduction/version-history/951-release-notes
release-notesRelease Notes
https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-31351
Advisory
https://github.com/advisories/GHSA-46xh-7854-f568
Advisory
https://nvd.nist.gov/vuln/detail/CVE-2026-8205

Link	Providers	Tags
https://documentation.concretecms.org/9-x/developers/introduction/version-history/951-release-notes		release-notesRelease Notes
https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-31351		Advisory
https://github.com/advisories/GHSA-46xh-7854-f568		Advisory
https://nvd.nist.gov/vuln/detail/CVE-2026-8205