CVE-2026-7888
Deferred Deferred - Pending Action
PHP Object Injection in Concrete CMS

Publication date: 2026-06-03

Last updated on: 2026-06-03

Assigner: ConcreteCMS

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.
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Meta Information
Published
2026-06-03
Last Modified
2026-06-03
Generated
2026-06-24
AI Q&A
2026-06-03
EPSS Evaluated
2026-06-22
NVD
CVE-2026-7888
EUVD
EUVD-2026-34164
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
concrete_cms concrete_cms to 9.5.2 (exc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-502 The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.
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Impact Analysis

This vulnerability can have a high impact on the affected system. An unauthenticated attacker with local access can exploit it to instantiate arbitrary PHP objects, potentially compromising confidentiality, integrity, and availability of the system.

Mitigation Strategies

To mitigate the PHP Object Injection vulnerability in Concrete CMS versions below 9.5.2, you should upgrade to version 9.5.2 or later where the issue has been fixed.

The fix involves adding the allowed_classes restriction to the unserialize() calls in the Workflow, Form block, and File/Set components to prevent arbitrary PHP object instantiation.

Executive Summary

CVE-2026-7888 is a security vulnerability in Concrete CMS versions below 9.5.2 involving PHP Object Injection. This occurs because unserialize() calls in the Workflow, Form block, and File/Set components do not restrict allowed_classes, allowing an attacker to instantiate arbitrary PHP objects if a malicious serialized payload is placed in the database.

Compliance Impact

The vulnerability in Concrete CMS allows PHP Object Injection, which can lead to high impacts on confidentiality, integrity, and availability of data.

Such impacts can potentially affect compliance with common standards and regulations like GDPR and HIPAA, which require protection of sensitive data and system integrity.

However, the provided information does not explicitly state the direct effects on compliance with these standards.

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