Concrete CMS versions 9.0.0 to 9.5.2 stored the Page Container icon value submitted through the dashboard without validating it against the set of known container icons. The unvalidated value was later concatenated into the src attribute of an img tag by a helper that did not encode attribute output, and was rendered raw in the Containers dashboard list and editor views. A user with delegated access to the Page Containers dashboard could store a crafted icon value that broke out of the src attribute and executed script in the authenticated session of another editor or administrator who viewed the list, enabling session token theft and privileged dashboard actions. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 7.0 with vector CVSS:4.0/AV:A/AC:L/AT:N/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N. Thanks Andrew Gonzalez for reporting.
History

Fri, 18 Sep 2026 21:30:00 +0000

Type Values Removed Values Added
CPEs cpe:2.3:a:concretecms:concrete_cms:*:*:*:*:*:*:*:*
Metrics cvssV3_1

{'score': 5.4, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N'}


Tue, 15 Sep 2026 15:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Tue, 15 Sep 2026 02:15:00 +0000

Type Values Removed Values Added
First Time appeared Concretecms
Concretecms concrete Cms
Vendors & Products Concretecms
Concretecms concrete Cms

Mon, 14 Sep 2026 21:00:00 +0000

Type Values Removed Values Added
Description Concrete CMS versions 9.0.0 to 9.5.2 stored the Page Container icon value submitted through the dashboard without validating it against the set of known container icons. The unvalidated value was later concatenated into the src attribute of an img tag by a helper that did not encode attribute output, and was rendered raw in the Containers dashboard list and editor views. A user with delegated access to the Page Containers dashboard could store a crafted icon value that broke out of the src attribute and executed script in the authenticated session of another editor or administrator who viewed the list, enabling session token theft and privileged dashboard actions. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 7.0 with vector CVSS:4.0/AV:A/AC:L/AT:N/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N. Thanks Andrew Gonzalez for reporting.
Title Concrete CMS 9.0.0 to 9.5.2 is vulnerable to Stored XSS via Page Container icon
Weaknesses CWE-79
References
Metrics cvssV4_0

{'score': 7, 'vector': 'CVSS:4.0/AV:A/AC:L/AT:N/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: ConcreteCMS

Published: 2026-09-14T20:14:25.577Z

Updated: 2026-09-15T14:45:47.911Z

Reserved: 2026-08-27T18:18:39.738Z

Link: CVE-2026-81903

cve-icon Vulnrichment

Updated: 2026-09-15T14:45:44.899Z

cve-icon NVD

Status : Analyzed

Published: 2026-09-14T21:17:26.400

Modified: 2026-09-18T19:12:09.993

Link: CVE-2026-81903

cve-icon Redhat

No data.