CVE-2026-8340
Concrete CMS is vulnerable to CSRF via Backend\File::approveVersion
EPSS 0.10%
Description
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an attacker-chosen previously-uploaded version (downgrade to an older version of a file, or activation of a co-editor's unpublished version). Thanks Winston Crooker for reporting.
How to fix CVE-2026-8340
To remediate CVE-2026-8340, upgrade the affected package to a fixed version below.
- Packagist/concrete5/concrete5—upgrade to 9.5.1 or later
Is CVE-2026-8340 being exploited?
Low — EPSS is 0.1%, meaning exploitation activity has not been observed at scale.
Affected packages (1)
- from 0, < 9.5.1
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 4.0 | — | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N |