TI-2026-06942 Aliases CVE-2026-7888 GHSA-52pr-7vmf-2w7x

Deserialization of untrusted data in Concrete CMS

LOW 37CWE-502Published 2026-06-03 · Updated 2026-09-11

Key facts

Attack vector: Local
Privileges required: High
User interaction: None
Attack complexity: Low
Attack requirements: None
Impact type: Code execution
Confidentiality · integrity · availability: High · High · High
Fix status: Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub. Impact type from CWE-502.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00155 4th percentileScored 2026-11-07

Fix Fixed concrete5/concrete5 (Packagist): 9.5.2

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: No
Technical impact: Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
—	concrete5/concrete5 (Packagist)	before 9.5.2	9.5.2	Patch available	GHSA-52pr-7vmf-2w7x

concrete5/concrete5 (Packagist) Vendor— Affected before 9.5.2 Fixed in 9.5.2 Patch available GHSA-52pr-7vmf-2w7x

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPE	Versions	Role	Vendor
cpe:2.3:a:concretecms:concrete_cms::::::::	—	—	Concrete CMS

cpe:2.3:a:concretecms:concrete_cms:*:*:*:*:*:*:*:* Versions — — ·Concrete CMS

Remediation

Fix · GHSA-52pr-7vmf-2w7x concrete5/concrete5 (Packagist) Fixed in 9.5.2 Advisory →

Timeline

2026-10-02 Threatist record created from CVE-2026-7888
2026-10-03 Alias added: GHSA-52pr-7vmf-2w7x

References

Advisory 1

https://nvd.nist.gov/vuln/detail/CVE-2026-7888

Other 3

TI-2026-23602 ConcreteCMS v9.4.7 contains a Denial of Service (DoS) vulnerability in the File Manager… CVSS 3.1MEDIUM 6.5
TI-2023-23992 A Cross Site Scripting (XSS) vulnerability in Concrete CMS from versions 9.2.0 to 9.2.2… CVSS 3.1MEDIUM 5.4
TI-2023-26495 Concrete CMS before 8.5.13 and 9.x before 9.2.2 allows unauthorized access because… CVSS 3.1CRITICAL 9.8
TI-2026-14907 Missing authorization in Concrete CMS CVSS 4.0HIGH 8.7
TI-2022-06200 Cleartext transmission of sensitive information in https://github.com/concrete5/concrete5 CVSS 3.1CRITICAL 9.8
TI-2021-17294 An issue was discovered in Concrete CMS through 8.5.5. CVSS 3.1CRITICAL 9.8

See all 220 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences