Concrete CMS up to 9.5.3 Dashboard getTimezoneDisplayName uTimezone cross site scripting

Summaryinfo

A vulnerability marked as problematic has been reported in Concrete CMS up to 9.5.3. The impacted element is the function Date::getTimezoneDisplayName of the component Dashboard. This manipulation of the argument uTimezone causes cross site scripting. The identification of this vulnerability is CVE-2026-85385. It is possible to initiate the attack remotely. There is no exploit available.

Detailsinfo

A vulnerability has been found in Concrete CMS up to 9.5.3 and classified as problematic. Affected by this vulnerability is the function Date::getTimezoneDisplayName of the component Dashboard. The manipulation of the argument uTimezone with an unknown input leads to a cross site scripting vulnerability. The CWE definition for the vulnerability is CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. As an impact it is known to affect integrity. The summary by CVE is:

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.

It is possible to read the advisory at documentation.concretecms.org. This vulnerability is known as CVE-2026-85385 since 09/03/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. It demands that the victim is doing some kind of user interaction. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1059.007 according to MITRE ATT&CK.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Type

• Content Management System

Name

• Concrete CMS

Version

• 9.5.0
• 9.5.1
• 9.5.2
• 9.5.3

License

• open-source

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