Vulnerability intelligence

CVE-2026-8134

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.

CVSS Score

9.4

Critical

EPSS — Exploit Probability

0.7%

Riskier than 52% of all CVEs · checked 2026-09-07

Exploitation

Not in CISA KEV

KEV does not include every exploited vulnerability

Remediation

Patch available

Vendor fix published