CVE-2026-8139
Analyzed Analyzed - Analysis Complete
Stored XSS in Concrete CMS via External-Link Page

Publication date: 2026-05-21

Last updated on: 2026-05-26

Assigner: ConcreteCMS

Description
Concrete CMS 9.5.0 and below is vulnerable to Stored XSS via external-link page cvName because updateCollectionAliasExternal bypasses being sanitized. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 2.0 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N.  Thanks Yonatan Drori (Tenzai) for reporting.
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Meta Information
Published
2026-05-21
Last Modified
2026-05-26
Generated
2026-06-11
AI Q&A
2026-05-22
EPSS Evaluated
2026-06-10
NVD
CVE-2026-8139
EUVD
EUVD-2026-31380
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
concretecms concrete_cms to 9.5.0 (inc)
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Exploitability
CWE
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KEV
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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.
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Executive Summary

This vulnerability affects Concrete CMS version 9.5.0 and below. It is a Stored Cross-Site Scripting (XSS) issue that occurs via the external-link page parameter named cvName. The problem arises because the function updateCollectionAliasExternal does not properly sanitize input, allowing malicious scripts to be stored and later executed in users' browsers.

Impact Analysis

The vulnerability can allow attackers to inject malicious scripts into the website that will be stored and executed when other users visit the affected pages. This can lead to unauthorized actions performed on behalf of users, theft of sensitive information, or other malicious activities. However, the CVSS score of 2.0 indicates a relatively low severity, suggesting limited impact under certain conditions.

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