CVE-2026-3242: Concrete CMS has a stored Cross-site Scripting (XSS) vulnerability

March 4, 2026

In Concrete CMS below version 9.4.8, a rogue administrator can add stored XSS via the Switch Language block.

The Concrete CMS security team gave thanks M3dium for reporting.

References

documentation.concretecms.org/9-x/developers/introduction/version-history/948-release-notes
github.com/advisories/GHSA-w9qg-chfh-g3q9
github.com/concretecms/concretecms
github.com/concretecms/concretecms/pull/12826
nvd.nist.gov/vuln/detail/CVE-2026-3242

Code Behaviors & Features

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