Vulnerability Description
Concrete CMS 9.5.0 and below fails to sanitize path traversal sequences in the ptComposerFormLayoutSetControlCustomTemplate field when saving page type composer form layouts. An authenticated rogue administrator with composer form editing rights can exploit this to include arbitrary readable files on the server. Combined with the file uploader's extension-only validation (which permits PHP code in files saved with image extensions like .png), this can result in authenticated remote code execution. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 9.4 with vector CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H Thanks Yonatan Drori (Tenzai) for reporting.
Related Weaknesses (CWE)
References
FAQ
What is CVE-2026-8134?
CVE-2026-8134 is a documented vulnerability. Concrete CMS 9.5.0 and below fails to sanitize path traversal sequences in the ptComposerFormLayoutSetControlCustomTemplate field when saving page type composer form layouts. An authenticated rogue ad...
How severe is CVE-2026-8134?
CVSS scoring is not yet available for CVE-2026-8134. Check NVD for updates.
Is there a patch for CVE-2026-8134?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.