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Description

Concrete CMS below 9.5.2 is vulnerable to PHP Object Injection via unserialize() calls in the Workflow, Form block, and File/Set components that lack the allowed_classes restriction. An unauthenticated attacker may trigger arbitrary PHP object instantiation if a malicious serialized payload has been placed in the database. Thanks XananasX7 and Sanjorn Keeratirungsan (dizconnect) for both independently reporting. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 8.4 with vector CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N.

PUBLISHED Reserved 2026-05-05 | Published 2026-06-03 | Updated 2026-06-03 | Assigner ConcreteCMS




HIGH: 8.4CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Problem types

CWE-502 Deserialization of untrusted data

Product status

Default status
unaffected

5.0 (git) before 9.5.2
affected

Credits

XananasX7 remediation developer

Sanjorn Keeratirungsan (dizconnect) finder

References

documentation.concretecms.org/...n-history/952-release-notes release-notes

cve.org (CVE-2026-7888)

nvd.nist.gov (CVE-2026-7888)

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