High 8.5Published Sep 15, 2026

CVE-2026-81894Concrete CMS 9.5.2 and below is vulnerable to Stored DOM-based Cross-site Scripting (XSS) in the Gallery block image Caption field

Updated under an hour ago (2026-10-19 07:30 UTC)

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Exploited in the last 30 days

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.

CVSS: 8.5 HIGH (v4.0, CNA)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
Weakness (CWE): CWE-89
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: ConcreteCMS
NVD analysis: Analyzed
Record last updated: Sep 22, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Concrete CMS Concrete CMS concrete_cms:concrete_cms (from the name)	from 5.0.0 through 9.5.2	CNA record
concretecms concrete_cms concretecms:concrete_cms	before 9.5.3	NVD

References

https://documentation.concretecms.org/developers/introduction/version-history/953-release-notesrelease-notes, broken-link

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.