CVE-2026-104890: Kunstmaan Bundles-CMS

High severity, CVSS 7.2. EPSS: 0.4% chance of exploitation in the next 30 days.

Kunstmaan CMS is an open source content management system based on the Symfony framework. Prior to 7.3.2, src/Kunstmaan/MediaBundle/Helper/File/FileHandler.php performs the blacklisted_extensions check case-sensitively in FileHandler::getFilePath and lowercases the stored extension afterward. An authenticated backend user with media access can upload a mixed-case executable extension such as PHP that bypasses the check and is stored in the web-accessible media directory with an executable lowercase extension. The default blacklist also omits several server-executable extension types, allowing the same code-execution impact where the web server executes uploaded files. This issue is fixed in version 7.3.2.

Affected products

• Kunstmaan Bundles-CMS: before 7.3.1 (fixed in 7.3.1)
• Kunstmaan Kunstmaanbundlescms: before 7.3.1 (fixed in 7.3.1)
• Kunstmaan Media-Bundle: before 7.3.1 (fixed in 7.3.1)

Published 2026-10-05. Last modified 2026-10-07.