---
id: CVE-2026-85385
title: >-
  Concrete CMS below 9.5.4 did not validate the user timezone value (uTimezone)
  on write and rendered it without output encoding on the Dashboard user
  management page, where Date::getTimezoneDisplayName() returns any non-IANA
  value unchang…
summary: >-
  Concrete CMS below 9.5.4 did not validate the user timezone value (uTimezone)
  on write and rendered it without output encoding on the Dashboard user
  management page, where Date::getTimezoneDisplayName() returns any non-IANA
  value unchang…
severity: critical
cvss: 9.6
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H'
cwe:
  - CWE-79
vendor: concretecms
product: concrete_cms
affected:
  - concrete_cms < 9.5.4
patched:
  - concrete_cms 9.5.4
published: '2026-09-16'
updated: '2026-09-21'
sourceUpdated: '2026-09-21T17:52:41.260'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-85385'
references:
  - url: >-
      https://documentation.concretecms.org/developers/introduction/version-history/954-release-notes
    label: ff5b8ace-8b95-4078-9743-eac1ca5451de
tags:
  - nvd
  - cve.org
epss: 0.00502
epssPercentile: 0.40332
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-09-17T17:34:47.620315Z'
scores:
  nvd: 9.6
  cna: 7.7
ingestedAt: '2026-09-16T16:59:56.553Z'
---

## Overview

Concrete CMS below 9.5.4 did not validate the user timezone value (uTimezone) on write and rendered it without output encoding on the Dashboard user management page, where Date::getTimezoneDisplayName() returns any non-IANA value unchanged. A stored cross-site scripting payload saved in this field executed in an administrator's browser when they viewed the affected user in the Dashboard, running script in the admin session (for example to read CSRF tokens, create administrator accounts, or change site settings). In Concrete CMS 9.5.3 the field became reachable by unauthenticated visitors through public registration; in Concrete CMS below 9.5.3,  the same field was reachable by any authenticated user through the account profile editor. Exploitation required concrete.misc.user_timezones to be enabled (off by default), and the unauthenticated path additionally required public registration to be enabled. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 7.7 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N. Thanks Suraj Bhosale for reporting.

## Affected

- `concrete_cms < 9.5.4`

## Remediation

Upgrade past the affected range:

- `concrete_cms 9.5.4`