CVE-2021-47735: Cmsimple

High severity, CVSS 8.8. EPSS: 0.9% chance of exploitation in the next 30 days.

CMSimple 5.4 contains an authenticated remote code execution vulnerability that allows logged-in attackers to inject malicious PHP code into template files. Attackers can exploit the template editing functionality by crafting a reverse shell payload and saving it through the template editing endpoint with a valid CSRF token.

Affected products

• Cmsimple Cmsimple: version 5.4 only

Published 2025-12-23. Last modified 2026-06-17.