---
id: CVE-2026-81894
title: >-
  Concrete CMS 9.5.2 and below is vulnerable to stored DOM-based Cross-site
  Scripting (XSS) via the Gallery block's per-image Caption field because the
  bundled Magnific Popup lightbox script
  (concrete/js/features/imagery/frontend.js) re-pa…
summary: >-
  Concrete CMS 9.5.2 and below is vulnerable to stored DOM-based Cross-site
  Scripting (XSS) via the Gallery block's per-image Caption field because the
  bundled Magnific Popup lightbox script
  (concrete/js/features/imagery/frontend.js) re-pa…
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-89
  - CWE-79
vendor: concretecms
product: concrete_cms
affected:
  - concrete_cms < 9.5.3
patched:
  - concrete_cms 9.5.3
published: '2026-09-15'
updated: '2026-09-22'
sourceUpdated: '2026-09-22T19:16:52.367'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-81894'
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: 0.00237
epssPercentile: 0.13164
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-09-22T18:05:47.459277Z'
scores:
  nvd: 5.4
  cna: 8.5
ingestedAt: '2026-09-15T17:41:02.865Z'
---

## Overview

Concrete CMS 9.5.2 and below is vulnerable to stored DOM-based Cross-site Scripting (XSS) via the Gallery block's per-image Caption field because the bundled Magnific Popup lightbox script (concrete/js/features/imagery/frontend.js) re-parses the attribute-decoded caption as HTML through jQuery's .append() in titleSrc instead of inserting it as text. A user with permission to edit a page containing a Gallery block can store a caption that executes in the browser of any visitor who opens that image's lightbox. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 8.5 with vector CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N. Thanks Yonatan Drori (Tenzai) for reporting.

## Affected

- `concrete_cms < 9.5.3`

## Remediation

Upgrade past the affected range:

- `concrete_cms 9.5.3`