CVE-2026-8134
HighSummary
Concrete CMS version 9.5.0 and below fails to sanitize path traversal sequences in the ptComposerFormLayoutSetControlCustomTemplate field when saving page type composer form layouts. A rogue administrator with composer form editing rights can exploit this vulnerability to include arbitrary readable files on the server.
Risk Assessment
This vulnerability can lead to authenticated remote code execution, posing a serious threat to the security of the system and the organization's data.
Recommendation
It is recommended to update Concrete CMS to the latest version to mitigate this vulnerability and review administrator permissions to limit composer form editing capabilities.
Original NVD description (English source)
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.