---
id: CVE-2026-81920
title: >-
  Concrete CMS below 9.5.3 was vulnerable to Cross-Site Request Forgery in the
  dashboard SEO Excluded Words page
summary: >-
  Concrete CMS below 9.5.3 was vulnerable to Cross-Site Request Forgery in the
  dashboard SEO Excluded Words page. The reset() controller action cleared the
  administrator-configured reserved-word list (concrete.seo.exclude_words) but
  did no…
severity: medium
cvss: 4.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N'
cwe:
  - CWE-352
vendor: concretecms
product: concrete_cms
affected:
  - concrete_cms < 9.5.3
patched:
  - concrete_cms 9.5.3
published: '2026-09-15'
updated: '2026-09-18'
sourceUpdated: '2026-09-18T15:27:27.317'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-81920'
references:
  - url: >-
      https://documentation.concretecms.org/developers/introduction/version-history/953-release-notes
    label: ff5b8ace-8b95-4078-9743-eac1ca5451de
tags:
  - nvd
  - cve.org
  - score-dispute
epss: 0.00177
epssPercentile: 0.06419
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-15T19:40:50.225213Z'
scores:
  nvd: 4.3
  cna: 2.3
ingestedAt: '2026-09-15T19:42:58.809Z'
---

## Overview

Concrete CMS below 9.5.3 was vulnerable to Cross-Site Request Forgery in the dashboard SEO Excluded Words page. The reset() controller action cleared the administrator-configured reserved-word list (concrete.seo.exclude_words) but did not validate the anti-CSRF token that the reset modal emitted, and it did not restrict the request to the POST method. A remote attacker who lured an authenticated user with SEO access to a crafted page could revert the reserved-word list to its default and silently alter future URL-slug generation for pages, files, topics, and other objects created through the Text urlify service, undoing the site's configured SEO slug policy. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 2.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks riodrwn for reporting.

## Affected

- `concrete_cms < 9.5.3`

## Remediation

Upgrade past the affected range:

- `concrete_cms 9.5.3`