CVE-2021-40098: Concretecms Concrete CMS

Critical severity, CVSS 9.8. EPSS: 1.6% chance of exploitation in the next 30 days.

An issue was discovered in Concrete CMS through 8.5.5. Path Traversal leading to RCE via external form by adding a regular expression.

Affected products

• Concretecms Concrete CMS: up to and including 8.5.5

Published 2021-09-27. Last modified 2026-06-17.