Concrete CMS below 9.5.3 does not apply HTML output escaping to the file description and tags fields when rendering the Document Library block, so a user with permission to edit file properties could store a script payload that executed in the browser of any visitor to a page displaying the block with the description or tags column enabled, including unauthenticated visitors. Successful exploitation could allow theft of session data or actions performed in the visitor's context. The block controller returned the description and tags values without the h() escaping already applied to the title column, and the block view template wrote the returned value directly into the results table The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 5.1 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:L/VI:L/VA:N/SC:H/SI:H/SA:N. Thanks Nguyen Manh Thuan for reporting.

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History

Fri, 11 Sep 2026 23:45:00 +0000

Type Values Removed Values Added
Description Concrete CMS below 9.5.3 does not apply HTML output escaping to the file description and tags fields when rendering the Document Library block, so a user with permission to edit file properties could store a script payload that executed in the browser of any visitor to a page displaying the block with the description or tags column enabled, including unauthenticated visitors. Successful exploitation could allow theft of session data or actions performed in the visitor's context. The block controller returned the description and tags values without the h() escaping already applied to the title column, and the block view template wrote the returned value directly into the results table The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 5.1 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:L/VI:L/VA:N/SC:H/SI:H/SA:N. Thanks Nguyen Manh Thuan for reporting.
Title Concrete CMS below 9.5.3 is vulnerable to Stored XSS in the Document Library block file description and tags
Weaknesses CWE-79
References
Metrics cvssV4_0

{'score': 5.1, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:L/VI:L/VA:N/SC:H/SI:H/SA:N'}


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cve-icon MITRE

Status: PUBLISHED

Assigner: ConcreteCMS

Published:

Updated: 2026-09-11T20:16:06.332Z

Reserved: 2026-08-27T18:23:01.365Z

Link: CVE-2026-81917

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-09-11T21:17:20.747

Modified: 2026-09-11T21:17:20.747

Link: CVE-2026-81917

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-09-12T07:00:14Z

Weaknesses