CVE-2026-3452
HIGH
GHSA-gj26-w59c-29mf
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
Lifecycle Timeline
3Description
Concrete CMS below version 9.4.8 is vulnerable to Remote Code Execution by stored PHP object injection into the Express Entry List block via the columns parameter. An authenticated administrator can store attacker-controlled serialized data in block configuration fields that are later passed to unserialize() without class restrictions or integrity checks. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 8.9 with vector CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H. Thanks YJK ( @YJK0805 https://hackerone.com/yjk0805 ) of ZUSO ART https://zuso.ai/ for reporting.
Analysis
Remote code execution in Concrete CMS prior to version 9.4.8 stems from unsafe deserialization of PHP objects in the Express Entry List block configuration. An authenticated administrator can inject malicious serialized data through the columns parameter that executes arbitrary code when unserialized without validation. …
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Remediation
Within 24 hours: Identify all Concrete CMS instances and their versions; assess which systems use Express Entry List blocks. Within 7 days: Apply vendor patch to upgrade all instances to version 9.4.8 or later; verify patches are successfully deployed. …
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External POC / Exploit Code
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