---
id: CVE-2026-68526
title: >-
  Concrete CMS before 9.5.3 did not validate an anti-CSRF token in the Calendar
  event duplicate dialog controller
  (concrete/controllers/dialog/event/duplicate.php) submit() action, which
  duplicated a calendar event after checking only canA…
summary: >-
  Concrete CMS before 9.5.3 did not validate an anti-CSRF token in the Calendar
  event duplicate dialog controller
  (concrete/controllers/dialog/event/duplicate.php) submit() action, which
  duplicated a calendar event after checking only canA…
severity: medium
cvss: 4.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N'
cwe:
  - CWE-352
vendor: concretecms
product: concrete_cms
affected:
  - concrete_cms < 9.5.3
patched:
  - concrete_cms 9.5.3
published: '2026-09-11'
updated: '2026-09-25'
sourceUpdated: '2026-09-25T20:41:17.633'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-68526'
references:
  - url: >-
      https://documentation.concretecms.org/9-x/developers/introduction/version-history/953-release-notes
    label: ff5b8ace-8b95-4078-9743-eac1ca5451de
tags:
  - nvd
  - cve.org
epss: 0.00239
epssPercentile: 0.13321
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-14T12:49:00.476469Z'
scores:
  nvd: 4.3
  cna: 5.3
ingestedAt: '2026-09-14T15:23:07.428Z'
---

## Overview

Concrete CMS before 9.5.3 did not validate an anti-CSRF token in the Calendar event duplicate dialog controller (concrete/controllers/dialog/event/duplicate.php) submit() action, which duplicated a calendar event after checking only canAccess() and the per-resource canAddCalendarEvent() permission, so a crafted cross-site request could cause an authenticated user with add-event permission to create duplicate CalendarEvents and CalendarEventVersions records under their own authority. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 5.3 with vector CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Winston Crooker for reporting.

## Affected

- `concrete_cms < 9.5.3`

## Remediation

Upgrade past the affected range:

- `concrete_cms 9.5.3`