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CVE-2026-81899

Concrete CMS 9.0 to 9.5.2 is vulnerable to Stored XSS via group folder name on the Members > Groups dashboard

CVSS 4.0 7.3 HIGHCheck source for fixed versionsKEV status unknown

Original advisory

cve-program · CVE-2026-81899

Published

Concrete CMS 9.0.0 to 9.5.2 stored group folder names without sanitization and printed them unescaped on the Members > Groups dashboard page, resulting in stored cross-site scripting. The add and edit group-folder handlers stored the submitted folder name without neutralizing HTML, and the group search grid returned it without output encoding, so the Groups dashboard rendered the name as live markup. An authenticated user holding the Add Group Folder permission could store a script payload as a folder name that executed in the session of any administrator who viewed the Groups dashboard, enabling session and token theft and any action available in the administrator's context. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 7.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N. Thanks Lý Chấn Hưng (hunglyvn) for reporting.

Read the publisher's advisory

Affected versions, risk and source history

cve-program · CVE-2026-81899

Published

Concrete CMS

https://github.com/concretecms/concretecms

Publisher's version information

Shown as published. These rules are not interpreted as NuGet package version ranges.

{
                    "vendor": "Concrete CMS",
                    "product": "Concrete CMS",
                    "collectionURL": "https://github.com/concretecms/concretecms",
                    "repo": "https://github.com/concretecms/concretecms",
                    "versions": [
                        {
                            "status": "affected",
                            "version": "9.0.0",
                            "lessThanOrEqual": "9.5.2",
                            "versionType": "git"
                        }
                    ],
                    "defaultStatus": "unaffected"
                }

Original source record · Cite this exact observation · Complete original publisher JSON