TI-2026-07407 Aliases CVE-2026-8426 GHSA-5rj5-gfmr-hrc3

Cross-site request forgery in Concrete CMS

LOW 34CWE-352Published 2026-05-21 · Updated 2026-05-22

Key facts

Attack vector: Network
Privileges required: None
User interaction: Active
Attack complexity: High
Attack requirements: Present
Impact type: Tampering, 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-352 and CWE-829.

Summary

Concrete CMS 9.5.0 and below does not validate a CSRF token before processing requests to /dashboard/extend/update/prepare_remote_upgrade/<remoteMPID>. An attacker who controls the remote package returned for a known marketplace item ID can overwrite the package PHP on disk and force its upgrade() method to execute in a single browser navigation. This results in remote code execution as the web server user. In order to be vulnerable, the victim must be passing canInstallPackages, victim site must be connected to the Concrete marketplace; and the attacker controls the package returned for a marketplace item ID already installed on the victim site. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 7.5 with vector CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N. Thanks https://github.com/maru1009 for reporting.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00171 6th percentileScored 2026-11-07

Fix Fixed concrete5/concrete5 (Packagist): 9.5.1

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 9.5.1	9.5.1	Patch available	GHSA-5rj5-gfmr-hrc3

concrete5/concrete5 (Packagist) Vendor— Affected before 9.5.1 Fixed in 9.5.1 Patch available GHSA-5rj5-gfmr-hrc3

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:concretecms:concrete_cms::::::::	before 9.5.1	Vulnerable	Concrete CMS

cpe:2.3:a:concretecms:concrete_cms:*:*:*:*:*:*:*:* Versions before 9.5.1 Vulnerable ·Concrete CMS

Remediation

Fix · GHSA-5rj5-gfmr-hrc3 concrete5/concrete5 (Packagist) Fixed in 9.5.1 Advisory →

Timeline

2026-10-02 Threatist record created from CVE-2026-8426
2026-10-03 Alias added: GHSA-5rj5-gfmr-hrc3

References

Advisory 1

https://nvd.nist.gov/vuln/detail/CVE-2026-8426

Other 2

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 197 →

Sources

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