CVE-2026-81926

Analyzed Analyzed - Analysis Complete

Cross-Site Scripting in Concrete CMS

Publication date: 2026-09-15

Last updated on: 2026-09-21

Assigner: ConcreteCMS

Description

Concrete CMS 9.4.0 through 9.5.2 did not escape colliding page paths before rendering them in the location panel's duplicate-path confirmation dialog. The panel's check endpoint returned the submitted path unmodified in its JSON response, and client-side JavaScript inserted each value into the dialog as raw HTML, so a crafted page path executed script in the editor's authenticated browser session. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 2.0 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:P/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N. Thanks Yonatan Drori from Tenzai for reporting.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-09-15

Last Modified

2026-09-21

Generated

2026-10-06

AI Q&A

2026-09-16

EPSS Evaluated

2026-10-04

NVD

CVE-2026-81926

EUVD

EUVD-2026-79940

Affected Vendors & Products

Vendor	Product	Version / Range
concretecms	concrete_cms	From 9.4.0 (inc) to 9.5.3 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-79	The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

Attack-Flow Graph

Executive Summary

Concrete CMS versions 9.4.0 through 9.5.2 had a flaw where page paths were not properly escaped before being displayed in a dialog box. This allowed attackers to inject malicious scripts into the page path, which would then execute in the browser of an authenticated editor when the dialog was shown.

Impact Analysis

If you are an editor or administrator using Concrete CMS versions 9.4.0 to 9.5.2, an attacker could trick you into viewing a specially crafted page path. This could lead to unauthorized actions being performed on your behalf, such as modifying content, stealing session data, or further compromising your account.

Compliance Impact

This vulnerability could lead to unauthorized access or data breaches, which may violate GDPR's integrity and confidentiality requirements or HIPAA's safeguards for protected health information. Organizations using affected versions must address this flaw to maintain compliance.

Mitigation Strategies

Update Concrete CMS to a version beyond 9.5.2 to address the unescaped page path issue. Review and sanitize all page paths to prevent crafted inputs. Monitor for unusual activity in the editor's browser session.

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