CVE-2026-8426

Published: Mag 21, 2026 Last Modified: Mag 26, 2026
ExploitDB:
Other exploit source:
Google Dorks:
HIGH 7,5
Source: ff5b8ace-8b95-4078-9743-eac1ca5451de
Attack Vector: network
Attack Complexity: high
Privileges Required: none
User Interaction: active
Confidentiality: N/A
Integrity: N/A
Availability: N/A
HIGH 8,8
Source: [email protected]
Attack Vector: network
Attack Complexity: low
Privileges Required: none
User Interaction: required
Scope: unchanged
Confidentiality: high
Integrity: high
Availability: high

Description

AI Translation Available

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.

EPSS (Exploit Prediction Scoring System)

Trend Analysis

EPSS (Exploit Prediction Scoring System)

Prevede la probabilità di sfruttamento basata su intelligence sulle minacce e sulle caratteristiche della vulnerabilità.

EPSS Score
0,0009
Percentile
0,2th
Updated

EPSS Score Trend (Last 7 Days)

352

Cross-Site Request Forgery (CSRF)

Stable
Abstraction: Compound Structure: Composite
Common Consequences
Security Scopes Affected:
Confidentiality Integrity Availability Non-Repudiation Access Control
Potential Impacts:
Gain Privileges Or Assume Identity Bypass Protection Mechanism Read Application Data Modify Application Data Dos: Crash, Exit, Or Restart
Applicable Platforms
Technologies: Web Based, Web Server
Likelihood of Exploit: Medium
View CWE Details
829

Inclusion of Functionality from Untrusted Control Sphere

Incomplete
Abstraction: Base Structure: Simple
Common Consequences
Security Scopes Affected:
Confidentiality Integrity Availability
Potential Impacts:
Execute Unauthorized Code Or Commands
Applicable Platforms
All platforms may be affected
View CWE Details
Application

Concrete Cms by Concretecms

Product Information
Vendor Concretecms
Product Concrete Cms
Version Range Affected
To 9.5.1 (exclusive)
cpe:2.3:a:concretecms:concrete_cms:*:*:*:*:*:*:*:*
Common Platform Enumeration - Standardized vulnerability identification
https://documentation.concretecms.org/9-x/developers/introd…
https://documentation.concretecms.org/9-x/developers/introduction/version-histo…