What is CVE-2026-8340?

CVE-2026-8340 is a medium-severity vulnerability in Concrete Cms, classified under Cross-Site Request Forgery (CSRF). CVSS score: 4.3/10. Published 2026-05-22.

How severe is CVE-2026-8340?

Medium severity. CVSS v3 base score is 4.3 out of 10.

CSRF in Concrete Cms

CVE-2026-8340

Concrete CMS 9.5.0 and below is vulnerable to CSRF via Backend\File::approveVersion. Victim with edit_file_contents permission is CSRF'd into publishing an attacker-chosen previously-uploaded version (downgrade to an older version of a fil…

Vulnerability class: CSRF (Cross-Site Request Forgery)

EPSS: 0.000 (5.9th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N.

Affected products

Concrete Cms — versions 5.0
Concretecms Concrete_cms

Weakness classification (CWE)

CWE-352 — Cross-Site Request Forgery (CSRF)

References

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

Frequently asked questions

What is CVE-2026-8340?: CVE-2026-8340 is a medium-severity vulnerability in Concrete Cms, classified under Cross-Site Request Forgery (CSRF). CVSS score: 4.3/10. Published 2026-05-22.
How severe is CVE-2026-8340?: Medium severity. CVSS v3 base score is 4.3 out of 10.