Concrete CMS below 9.5.3 is vulnerable to PHP Object Injection via unserialize()
calls in the Workflow, Form block, and File/Set components that lack the
allowed_classes restriction. The Form block and File/Set sinks were addressed in
9.5.2; the Workflow component sinks were addressed in 9.5.3. 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 independently reporting the original components, and sh4d0byss for
reporting the Workflow component wasn't fixed in 9.5.2. 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.

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-52pr-7vmf-2w7x Concrete CMS is vulnerable to PHP Object Injection via unserialize() calls in the Workflow, Form block, and File/Set components
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Fri, 11 Sep 2026 23:45:00 +0000

Type Values Removed Values Added
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. Concrete CMS below 9.5.3 is vulnerable to PHP Object Injection via unserialize() calls in the Workflow, Form block, and File/Set components that lack the allowed_classes restriction. The Form block and File/Set sinks were addressed in 9.5.2; the Workflow component sinks were addressed in 9.5.3. 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 independently reporting the original components, and sh4d0byss for reporting the Workflow component wasn't fixed in 9.5.2. 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.
Title 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. Concrete CMS below 9.5.3 is vulnerable to PHP Object Injection via unserialize() calls in the Workflow, Form block, and File/Set components that lack the allowed_classes restriction.

Wed, 03 Jun 2026 22:45:00 +0000

Type Values Removed Values Added
First Time appeared Concretecms
Concretecms concrete Cms
Vendors & Products Concretecms
Concretecms concrete Cms

Wed, 03 Jun 2026 19:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Wed, 03 Jun 2026 19:00:00 +0000

Type Values Removed Values Added
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.
Title 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.
Weaknesses CWE-502
References
Metrics cvssV4_0

{'score': 8.4, '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'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: ConcreteCMS

Published:

Updated: 2026-09-11T19:04:23.786Z

Reserved: 2026-05-05T20:23:08.863Z

Link: CVE-2026-7888

cve-icon Vulnrichment

Updated: 2026-06-03T19:07:52.022Z

cve-icon NVD

Status : Deferred

Published: 2026-06-03T19:16:38.910

Modified: 2026-09-11T20:18:54.320

Link: CVE-2026-7888

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-06-03T22:30:43Z

Weaknesses