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CVE-2026-85385

9.6, critical

Concrete CMS Cross-Site Scripting Vulnerability

NVD (opens in a new tab) CVE.org (opens in a new tab)
CVSS
9.6, critical critical CVSS v3.1
EPSS, next 30 days
0.5% higher than 41.6% of scored CVEs
Exploitation
No public evidence
Published
16 Sept 2026a month ago

Description

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.

Details

Vendor
Concrete CMS
Product
Concrete CMS
Weakness
CWE-79 (opens in a new tab)
Status
Analyzed
Updated
21 Sept 2026
Assigner
ff5b8ace-8b95-4078-9743-eac1ca5451de

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

References 1

Other references 1

The kind is read from NVD's tags where present and from the shape of the URL otherwise, so treat it as a hint.

Other Concrete CMS CVEs

Every Concrete CMS CVE we hold

Same vendor in what we hold, not a known link between the flaws.

  • CVE-2026-85387 Concrete CMS Insufficient Session Expiration Vulnerability EPSS 0.3% 7.1, high
  • CVE-2026-18110 Concrete CMS Missing Authorization Vulnerability EPSS 0.3% 7.5, high
  • CVE-2026-81895 Concrete CMS SQL Injection Vulnerability EPSS 0.5% 7.2, high
  • CVE-2026-18423 Concrete CMS Authorization Bypass Through User-Controlled Key Vulnerability EPSS 0.2% 7.1, high
  • CVE-2026-18424 Concrete CMS Server-Side Request Forgery Vulnerability EPSS 0.2% 7.1, high
  • CVE-2026-18119 Concrete CMS Cross-Site Scripting Vulnerability EPSS 0.3% 9, critical
  • CVE-2026-81901 Concrete CMS Missing Authorization Vulnerability EPSS 0.4% 8.7, high
  • CVE-2026-81902 Concrete CMS Cross-Site Request Forgery Vulnerability EPSS 0.2% 8.1, high

Beyond this page

Is CVE-2026-85385 in your network?

This page tells you how dangerous CVE-2026-85385 is out there. Whether it sits on one of your devices, only a scan of your own network can tell. That is what our systems do, every day, for the companies we protect.

  • EXYS7600 OCELOT

    Find it before attackers do

    Ocelot scans your network on a schedule and reports every vulnerability it finds by its CVE identifier, with its CVSS score and how many of your hosts are affected. A finding like CVE-2026-85385 comes with the devices to patch.

    Learn more about EXYS7600 OCELOT

  • EXYS7950 KONDRA

    Detect it if it's exploited

    Until the patch is applied, Kondra monitors your network, events and endpoints in real time. It keeps an inventory of the software installed on every endpoint, and its anomaly detection rules flag what an attacker does once inside.

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Check your exposure

Assembled from the NVD 2.0 API, the CISA Known Exploited Vulnerabilities Catalog and FIRST EPSS. Scores are as of our last collection on 17 Oct 2026, not the live upstream state.