CVE-2026-54611: Instantsoft ICMS2

Medium severity, CVSS 5.5. EPSS: 0.7% chance of exploitation in the next 30 days.

InstantCMS is a free and open source content management system. Versions prior to 2.18.2 have a Remote Code Execution (RCE) issue that allows remote authenticated attackers to execute any PHP code via the component installer. It is possible to upload a malicious component into the server, however, it won't be installed, but upload files will be executed. Normally all php files in upload folder are not executed, however, by uploading custom .htaccess it becomes possible. Version 2.18.2 contains a fix.

Affected products

• Instantsoft ICMS2: before 2.18.2 (fixed in 2.18.2)

Published 2026-09-08. Last modified 2026-09-09.