CVE-2026-8134 (GCVE-0-2026-8134)
Vulnerability from cvelistv5 – Published: 2026-05-21 20:13 – Updated: 2026-05-22 12:15
VLAI
EPSS
VEX
Title
Concrete CMS 9.5.0 and below is vulnerable to Authenticated RCE via Composer customTemplate Path Traversal leading to PHP File Inclusion
Summary
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.
Severity
SSVC
Exploitation: none
Automatable: no
Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-05-22 12:15 UTC
CWE
Assigner
ConcreteCMS
CNA
References
1 reference
| URL | Tags |
|---|---|
| https://documentation.concretecms.org/9-x/develop… | release-notes |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Concrete CMS | Concrete CMS |
Affected:
5.0 , ≤ 9.5.0
(git)
|
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