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CVE-2026-8421

CVE-2026-8421 · Concrete CMS 9.5.0 and below is vulnerable to CSRF on install_package() with conditional token bypass leading to RCE

This page contains facts from public vulnerability sources. Check the original advisory before updating.

Concrete CMS 9.5.0 and below contains a CSRF vulnerability in the install_package() method of concrete/controllers/single_page/dashboard/extend/install.php.  An attacker who can cause an authenticated administrator to visit a crafted page,  and who has placed or caused a package to be present under DIR_PACKAGES/<handle>/, can force the installation of that package without any CSRF protection. Package installation executes the package controller's install() method as the web server user, enabling remote code execution.  In order to be vulnerable, the victim must be passing canInstallPackages. 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.

CVSS 7.5 · High · EPSS 0.2% · Fix available

Published
Updated

Stack: php

Affected products and versions

  • concrete cms

    Versions
    • ≥ 5.0, ≤ 9.5.0: Affected (git)

    No fix published

  • concrete5/concrete5 Packagist

    Versions
    • 8.0
    • 8.0.1
    • 8.0.2
    • 8.0.3
    • 8.1.0
    • 8.2.0
    • 8.2.0RC2
    • 8.2.1
    • 8.3.0
    • 8.3.1
    • 8.3.2
    • 8.4.0
    • 8.4.0RC3
    • 8.4.0RC4
    • 8.4.1
    • 8.4.2
    • 8.4.3
    • 8.4.4
    • 8.4.5
    • 8.5.0
    • 8.5.0RC1
    • 8.5.0RC2
    • 8.5.1
    • 8.5.10
    • 8.5.11
    • 8.5.12
    • 8.5.13
    • 8.5.14
    • 8.5.15
    • 8.5.16
    • 8.5.17
    • 8.5.18
    • 8.5.19
    • 8.5.2
    • 8.5.20
    • 8.5.21
    • 8.5.3
    • 8.5.4
    • 8.5.5
    • 8.5.6
    • 8.5.6RC1
    • 8.5.7
    • 8.5.8
    • 8.5.9
    • 9.0.0
    • 9.0.0RC1
    • 9.0.0RC3
    • 9.0.0RC4
    • 9.0.1
    • 9.0.2
    • 9.1.0
    • 9.1.1
    • 9.1.2
    • 9.1.3
    • 9.2.0
    • 9.2.0RC2
    • 9.2.1
    • 9.2.2
    • 9.2.3
    • 9.2.4
    • 9.2.5
    • 9.2.6
    • 9.2.7
    • 9.2.8
    • 9.2.9
    • 9.3.0
    • 9.3.1
    • 9.3.2
    • 9.3.3
    • 9.3.4
    • 9.3.5
    • 9.3.6
    • 9.3.7
    • 9.3.8
    • 9.3.9
    • 9.4.0
    • 9.4.0RC1
    • 9.4.0RC2
    • 9.4.1
    • 9.4.2
    • 9.4.3
    • 9.4.4
    • 9.4.5
    • 9.4.6
    • 9.4.7
    • 9.4.8
    • 9.5.0
    • 9.5.0RC1
    • 9.5.0RC2
    Affected ranges
    • ECOSYSTEM: < 9.5.1

    Update to 9.5.1

Original sources

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