CVE-2026-85385 Concrete CMS - Stored XSS

Concrete CMS < 9.5.4 contains a stored cross-site scripting caused by lack of validation and output encoding of user timezone value on the Dashboard user management page, letting attackers execute scripts in administrator sessions, exploit requires concrete.misc.user_timezones enabled and either authenticated user or public registration enabled.

CVSS base score 9.6 /10
Critical
CISA KEV
Not listed
Public exploit
None known
Authentication
Not required
EPSS
0.50% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Stored XSS
Impact
Stored XSS
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
Published
16 September 2026
Updated
15 October 2026
Weakness
CWE-79

Vendor fix

Update to version 9.5.4 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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