CVE-2026-8428
Published: 21 May 2026
Summary
CVE-2026-8428 is a high-severity CSRF (CWE-352) vulnerability in Concretecms Concrete Cms. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 3.1th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-31340
Vulnerability details
Concrete CMS 9.5.0 and below emits a CSRF token in the local_available_update.php view ($token->output('do_update')) but the corresponding do_update() method in concrete/controllers/single_page/dashboard/system/update/update.php never calls $this->token->validate('do_update'). The form is rendered as a POST form, meaning the token reaches the browser, but because…
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the controller discards it without verification, an attacker can craft a cross-site POST that triggers a core CMS update to an attacker-specified version string. In order to be vulnerable, theictim must be passing canUpgrade()anda valid update version must be present under DIR_CORE_UPDATES. 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.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
CSRF flaw in public CMS update endpoint allows remote trigger of attacker-chosen core update (CWE-352/829), directly matching exploitation of a public-facing web application.
Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Awareness training educates users on avoiding untrusted links and actions that can be exploited via CSRF.
Limiting P2P file sharing technology reduces inclusion of functionality or resources from untrusted external control spheres.
Enforcing installation policies prevents users from including functionality obtained from untrusted control spheres.
The inventory process requires identifying and recording the origin of all components, making inclusion of functionality from untrusted control spheres easier to detect during reviews.
Requiring user re-entry of credentials for sensitive actions prevents automated forgery of requests without active user participation.
Requiring approval and monitoring of maintenance tools prevents inclusion and execution of functionality obtained from untrusted sources.
Unowned portable devices represent untrusted control spheres; the prohibition prevents inclusion of functionality or data from such sources.
Security testing regimens explicitly include checks for missing or ineffective anti-CSRF protections in web applications.