---
id: CVE-2026-81917
title: >-
  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 …
summary: >-
  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 …
severity: medium
cvss: 5.4
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N'
cwe:
  - CWE-79
vendor: concretecms
product: concrete_cms
affected:
  - concrete_cms < 9.5.3
patched:
  - concrete_cms 9.5.3
published: '2026-09-11'
updated: '2026-09-18'
sourceUpdated: '2026-09-18T15:18:54.377'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-81917'
references:
  - url: >-
      https://documentation.concretecms.org/developers/introduction/version-history/953-release-notes
    label: ff5b8ace-8b95-4078-9743-eac1ca5451de
tags:
  - nvd
  - cve.org
epss: 0.00237
epssPercentile: 0.13165
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-14T12:50:48.957058Z'
scores:
  nvd: 5.4
  cna: 5.1
ingestedAt: '2026-09-14T15:23:07.428Z'
---

## Overview

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.

## Affected

- `concrete_cms < 9.5.3`

## Remediation

Upgrade past the affected range:

- `concrete_cms 9.5.3`