What is CVE-2026-8426?

CVE-2026-8426 is a high-severity vulnerability in Concrete Cms, classified under Cross-Site Request Forgery (CSRF). CVSS score: 8.8/10. Published 2026-05-21.

How severe is CVE-2026-8426?

High severity. CVSS v3 base score is 8.8 out of 10.

CSRF in Concrete Cms

CVE-2026-8426

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 ca…

Vulnerability class: CSRF (Cross-Site Request Forgery)

EPSS: 0.001 (22.8th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

Affected products

Concrete Cms — versions 5.0
Concretecms Concrete_cms

Weakness classification (CWE)

CWE-352 — Cross-Site Request Forgery (CSRF)
CWE-829 — Inclusion of Functionality from Untrusted Control Sphere

References

ff5b8ace-8b95-4078-9743-eac1ca5451de (release-notes, Release Notes)

Frequently asked questions

What is CVE-2026-8426?: CVE-2026-8426 is a high-severity vulnerability in Concrete Cms, classified under Cross-Site Request Forgery (CSRF). CVSS score: 8.8/10. Published 2026-05-21.
How severe is CVE-2026-8426?: High severity. CVSS v3 base score is 8.8 out of 10.