Concrete CMS up to 9.5.0 height cross site scripting

Summaryinfo

A vulnerability marked as problematic has been reported in Concrete CMS up to 9.5.0. Affected is an unknown function. This manipulation of the argument height causes cross site scripting. The identification of this vulnerability is CVE-2026-8203. It is possible to initiate the attack remotely. There is no exploit available.

Detailsinfo

A vulnerability has been found in Concrete CMS up to 9.5.0 and classified as problematic. Affected by this vulnerability is an unknown code. The manipulation of the argument height with an unknown input leads to a cross site scripting vulnerability. The CWE definition for the vulnerability is 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. As an impact it is known to affect integrity. The summary by CVE is:

Concrete CMS 9.5.0 and below has Stored XSS on the height parameter. The controller does not validate or sanitize $height. Any user with editor privileges can inject malicious JavaScript that executes in the context of any visitor's browser, potentially leading to session hijacking, credential theft, or other malicious actions. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 7.3 with vector CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N. Thanks Alfin Joseph for reporting.

The weakness was shared by Alfin Joseph. The advisory is shared at documentation.concretecms.org. This vulnerability is known as CVE-2026-8203 since 05/09/2026. The exploitation appears to be difficult. The attack can be launched remotely. Additional levels of successful authentication are needed for exploitation. It demands that the victim is doing some kind of user interaction. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1059.007 for this issue.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Type

• Content Management System

Vendor

• Concrete

Name

• CMS

Version

• 9.0
• 9.1
• 9.2
• 9.3
• 9.4
• 9.5.0

License

• open-source

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CPE 2.2info

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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