CVE-2021-40105: Concretecms Concrete CMS

Medium severity, CVSS 6.1. EPSS: 0.7% chance of exploitation in the next 30 days.

An issue was discovered in Concrete CMS through 8.5.5. There is XSS via Markdown Comments.

Affected products

• Concretecms Concrete CMS: up to and including 8.5.5

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